# kb

id: microwave-radiometer-juno-20260505-0
file: data/en.wikipedia.org/wiki/Microwave_Radiometer_(Juno)-0.md
category: reference
title: Microwave Radiometer (Juno)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Microwave_Radiometer_(Juno)
date_saved: 2026-05-05T09:45:28.069249+00:00
instance: kb-cron
parent: microwave-radiometer-juno-20260505-0
summary:
Microwave Radiometer (MWR) is an instrument on the Juno orbiter sent to planet Jupiter. MWR is a multi-wavelength microwave radiometer for making observations of Jupiter's deep atmosphere. MWR can observe radiation from 1.37 to 50 cm in wavelength, from 600 MHz to 22 GHz in frequencies. This supports its goal of observing the previously unseen atmospheric features and chemical abundances hundreds of miles or kilometers into Jupiter's atmosphere. MWR is designed to detect six different frequencies in that range using separate antennas. MWR views Jupiter's microwave radiation so it can see up to hundreds of miles deep into the planet. In August 2016, as Juno swung closely by the planet MWR achieved a penetration of 200 to 250 miles (350 to 400 kilometers) below the surface cloud layer. MWR is designed to make observations below the cloud-tops, especially detecting the abundances of certain chemicals and determining dynamic features. These depths have not been observed before. MWR was launched aboard the Juno spacecraft on August 5, 2011 (UTC) from Cape Canaveral, USA, as part of the New Frontiers program, and after an interplanetary journey that including a swingby of Earth, entered a polar orbit of Jupiter on July 5, 2016 (UTC),


id: microwave-sounding-unit-20260505-0
file: data/en.wikipedia.org/wiki/Microwave_sounding_unit-0.md
category: reference
title: Microwave sounding unit
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Microwave_sounding_unit
date_saved: 2026-05-05T09:45:29.211966+00:00
instance: kb-cron
parent: microwave-sounding-unit-20260505-0
summary:
The microwave sounding unit (MSU) was the predecessor to the Advanced Microwave Sounding Unit (AMSU). The MSU was first launched aboard the TIROS-N satellite in late 1978 and provided global coverage (from Pole to Pole). It carries a 4-channel microwave radiometer, operating between 50 and 60 GHz. Spatial resolution on the ground was 2.5 deg in longitude and latitude (about 250 km circle). There were 9 different MSUs launched; the most recent one on NOAA-14. They provided measurements of the temperature of the troposphere and lower stratosphere until 1998, when the first AMSU was deployed. AMSU provides many more channels and finer resolution (about 50 km). Table 1 lists some characteristics of the MSU. The radiometer's antenna scans underneath the satellite through nadir, and its polarization vector rotates with the scan angle. In the table, "vertical polarization near nadir" means that the E-vector is parallel to the scan direction at nadir, and "horizontal polarization" means the orthogonal direction. Table 1 Radiometric characteristics of the Microwave Sounding Unit == Applications == The MSU was used by NOAA for meteorological analyses in combination with two infrared instruments, and sometimes alone, for post-analysis of weather events and other atmospheric phenomena such as waves.


id: mimos-ii-20260505-0
file: data/en.wikipedia.org/wiki/MIMOS_II-0.md
category: reference
title: MIMOS II
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/MIMOS_II
date_saved: 2026-05-05T09:45:30.407890+00:00
instance: kb-cron
parent: mimos-ii-20260505-0
summary:
MIMOS II is the miniaturised Mössbauer spectrometer, developed by Dr. Göstar Klingelhöfer at the Johannes Gutenberg University in Mainz, Germany, that is used on the Mars Exploration Rovers Spirit and Opportunity for close-up investigations on the Martian surface of the mineralogy of iron-bearing rocks and soils. MIMOS II uses a Cobalt-57 gamma ray source of about 300 mCi at launch which gave a 6-12 hr time for acquisition of a standard MB spectrum during the primary mission on Mars, depending on total Fe content and which Fe-bearing phases are present. Cobalt-57 has a half-life of only 271.8 days (h The MIMOS II sensorheads used snMars are approx 9 cm x 5 cm x 4 cm and weigh about 400g. The MIMOS II system also includes a circuit board of about 100g. == References ==


id: mini-tes-20260505-0
file: data/en.wikipedia.org/wiki/Mini-TES-0.md
category: reference
title: Mini-TES
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mini-TES
date_saved: 2026-05-05T09:45:31.559953+00:00
instance: kb-cron
parent: mini-tes-20260505-0
summary:
The Miniature Thermal Emission Spectrometer (Mini-TES) is an infrared spectrometer used for detecting the composition of a material (typically rocks) from a distance. By making its measurements in the thermal infrared part of the electromagnetic spectrum, it has the ability to penetrate through the dust coatings common to the Martian surface which is usually problematic for remote sensing observations. There is one on each of the two Mars Exploration Rovers. == Development == The Mini-TES was originally developed by Raytheon for the Department of Geological Sciences at Arizona State University. The Mini-TES is a miniaturized version of Raytheon's Mars Global Surveyor (MGS) TES, built by Arizona State University and Raytheon SAS’ Santa Barbara Remote Sensing. The MGS TES data helped scientists choose landing sites for the Spirit and Opportunity Mars explorer rovers. == Martian soil == The Mini-TES is used for identifying promising rocks and soils for closer examination, and to determine the processes that formed Martian rocks. It measures the infrared radiation that the target rock or object emits in 167 different wavelengths, providing information about the target's composition. One particular goal is to search for minerals that were formed by the action of water, such as carbonates and


id: modular-optoelectronic-multispectral-scanner-20260505-0
file: data/en.wikipedia.org/wiki/Modular_optoelectronic_multispectral_scanner-0.md
category: reference
title: Modular optoelectronic multispectral scanner
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Modular_optoelectronic_multispectral_scanner
date_saved: 2026-05-05T09:45:32.762948+00:00
instance: kb-cron
parent: modular-optoelectronic-multispectral-scanner-20260505-0
summary:
The modular optoelectronic multispectral scanner (MOMS) is a scanning system for spaceborne, geoscientific remote sensing applications used in satellite navigation systems for sensing atmospheric and oceanic systems. The scanner is combination of separate spectrometer blocks. == History == The modular optoelectronic multispectral scanner is an optical technology programme funded by the German Ministry for Research and Technology. It was jointly designed and developed by DLR, LMU and EADS Astrium. == Characteristics == The modular structure of MOMS makes it suitable for use in wide variety of geo-spatial missions, the modules being sensor, optical lens, electronics and filters. The first flight of MOMS yielded high-resolution images with 20x20 m ground pixel size from about 300 km orbital altitude. === MOMS-01 === MOMS01 consists of five instruments mounted on a carbon-fiber structure: The optical module with four objectives, eight arrays, and associated shutters. Each module represents one spectral band, consisted of filters, dual-lens optics, four CCD detector line-scanning arrays, and preamplifier electronics. A power box for overall power control. A logic box for all sensor function control (including real-time correction, and formatting of the source data stream from the optical module) A HDDT (high-density digital tape) recorder. A pressurized container for the


id: moonlight-20260505-0
file: data/en.wikipedia.org/wiki/MoonLIGHT-0.md
category: reference
title: MoonLIGHT
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/MoonLIGHT
date_saved: 2026-05-05T09:45:33.985632+00:00
instance: kb-cron
parent: moonlight-20260505-0
summary:
MoonLIGHT (Moon Laser Instrumentation for General relativity High accuracy Tests) is a laser retroreflector developed as a collaboration primarily between the University of Maryland in the United States, and the Italian National Institute for Nuclear Physics - National Laboratories of Frascati (INFN-LNF) to complement and expand on the Lunar Laser Ranging experiment started with the Apollo Program in 1969. MoonLIGHT was planned to be launched in July 2020 as a secondary payload on the MX-1E lunar lander built by the private company Moon Express. However, the launch of the MX-1E has been cancelled. In 2018 INFN proposed to the European Space Agency (ESA) the MoonLIGHT Pointing Actuators (MPAc) project and was contracted by ESA to deliver it. MPAc is an INFN development for ESA, with auxiliary support by the Italian Space Agency (ASI) for prototyping work. In 2021, ESA agreed with NASA to launch MPAc with a Commercial Lunar Payload Services (CLPS) mission. Nova-C, the lander on which MPAc will be integrated, is designed by Intuitive Machines and the landing site is Reiner Gamma. The expected launch date of the Nova-C mission carrying the instrument, IM-3, is in 2026. == Overview == Laser Ranging is a technique used to perform


id: mssta-20260505-0
file: data/en.wikipedia.org/wiki/MSSTA-0.md
category: reference
title: MSSTA
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/MSSTA
date_saved: 2026-05-05T09:45:35.207408+00:00
instance: kb-cron
parent: mssta-20260505-0
summary:
The Multi-Spectral Solar Telescope Array (MSSTA) was a sounding rocket payload built by Arthur B. C. Walker Jr. at Stanford University in the 1990s to test EUV/XUV imaging of the Sun using normal incidence EUV-reflective multilayer optics. == History == MSSTA contained a large number of individual telescopes (> 10), all trained on the Sun and all sensitive to slightly different wavelengths of ultraviolet light. Like all sounding rockets, MSSTA flew for approximately 14 minutes per mission, about 5 minutes of which were in space—just enough time to test a new technology or yield "first results" science. MSSTA is one of the last solar observing instruments to use photographic film rather than a digital camera system such as a CCD. MSSTA used film instead of a CCD in order to achieve the highest possible spatial resolution and to avoid the electronics difficulty presented by the large number of detectors that would have been required for its many telescopes. MSSTA and its sister rocket, NIXT, were prototypes for normal incidence extreme ultraviolet imaging telescopes that are in use today, as well as the historic EIT instrument aboard the SOHO spacecraft, and the TRACE spacecraft. MSSTA flew three times: once in 1991


id: multi-angle-imaging-spectroradiometer-20260505-0
file: data/en.wikipedia.org/wiki/Multi-angle_imaging_spectroradiometer-0.md
category: reference
title: Multi-angle imaging spectroradiometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Multi-angle_imaging_spectroradiometer
date_saved: 2026-05-05T09:45:36.352254+00:00
instance: kb-cron
parent: multi-angle-imaging-spectroradiometer-20260505-0
summary:
The multi-angle imaging spectroradiometer (MISR) is a scientific instrument on the Terra satellite launched by NASA on 18 December 1999. This device is designed to measure the intensity of solar radiation reflected by the Earth system (planetary surface and atmosphere) in various directions and spectral bands; it became operational in February 2000. Data generated by this sensor have been proven useful in a variety of applications including atmospheric sciences, climatology and monitoring terrestrial processes. The MISR instrument consists of an innovative configuration of nine separate digital cameras that gather data in four different spectral bands of the solar spectrum. One camera points toward the nadir, while the others provide forward and aftward view angles at 26.1°, 45.6°, 60.0°, and 70.5°. As the instrument flies overhead, each region of the Earth's surface is successively imaged by all nine cameras in each of four wavelengths (blue, green, red, and near-infrared). The data gathered by MISR are useful in climatological studies concerning the disposition of the solar radiation flux in the Earth's system. MISR is specifically designed to monitor the monthly, seasonal, and long-term trends of atmospheric aerosol particle concentrations including those formed by natural sources and by human activities, upper air winds


id: nadir-and-occultation-for-mars-discovery-20260505-0
file: data/en.wikipedia.org/wiki/Nadir_and_Occultation_for_Mars_Discovery-0.md
category: reference
title: Nadir and Occultation for Mars Discovery
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Nadir_and_Occultation_for_Mars_Discovery
date_saved: 2026-05-05T09:45:37.538199+00:00
instance: kb-cron
parent: nadir-and-occultation-for-mars-discovery-20260505-0
summary:
Nadir and Occultation for MArs Discovery (NOMAD) is a 3-channel spectrometer on board the ExoMars Trace Gas Orbiter (TGO) launched to Mars orbit on 14 March 2016. NOMAD is designed to perform high-sensitivity orbital identification of atmospheric components, concentration and temperature, their sources, loss, and cycles. It measures the sunlight reflected from the surface and atmosphere of Mars, and it analyses its wavelength spectrum to identify the components of the Martian atmosphere that may suggest a biological source. The Principal Investigator is Ann Carine Vandaele, from the Belgian Institute for Space Aeronomy, Belgium. == Overview == NOMAD is one of four science instruments on board the European ExoMars TGO orbiter. This spectrometer consists of three separate channels: solar occultation (SO), limb nadir and occultation (LNO), and ultraviolet and visible spectrometer (UVIS). The first two channels work in the infrared (2.2 to 4.3 μm); the third channel (UVIS) works in the UV-visible range (0.2 to 0.65 μm), which is able to measure ozone, sulphuric acid, and perform aerosol studies. Measurements are carried out during solar occultation, i.e. the instrument points toward the sunset as the orbiter moves toward or away the dark side of Mars. It also measures in nadir mode,


id: navcam-20260505-0
file: data/en.wikipedia.org/wiki/Navcam-0.md
category: reference
title: Navcam
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Navcam
date_saved: 2026-05-05T09:45:38.703648+00:00
instance: kb-cron
parent: navcam-20260505-0
summary:
Navcam, short for navigational camera, is a type of camera found on certain robotic rovers or spacecraft used for navigation without interfering with scientific instruments. Navcams typically take wide angle photographs that are used to plan the next moves of the vehicle or object tracking. == Overview == The Mars Curiosity rover has two pairs of black and white navigation cameras mounted on the mast to support ground navigation. The cameras have a 45 degree angle of view and use visible light to capture stereoscopic 3-D imagery. These cameras, like those on the Mars Pathfinder missions support use of the ICER image compression format. European Space Agency Rosetta spacecraft used a single camera with 5 degree field of view and 12 bit 1024x1024px resolution allowing for visual tracking on each of spacecraft approaches to the asteroids and finally the comet. == Gallery == == See also == Astrionics Hazard avoidance camera (Hazcam) Panoramic camera (Pancam) Optical, Spectroscopic, and Infrared camera OSIRIS List of NASA cameras on spacecraft Mars rover == References ==


id: odin-osiris-20260505-0
file: data/en.wikipedia.org/wiki/Odin-OSIRIS-0.md
category: reference
title: Odin-OSIRIS
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Odin-OSIRIS
date_saved: 2026-05-05T09:45:41.000273+00:00
instance: kb-cron
parent: odin-osiris-20260505-0
summary:
OSIRIS (Optical Spectrograph and InfraRed Imager System) is an instrument that measures vertical profiles of spectrally dispersed, limb scattered sunlight from the upper troposphere into the lower mesosphere. OSIRIS is one of two instruments on the Odin satellite, launched February, 2001 (the other instrument being a sub-mm radiometer) into a Sun-synchronous, 6 pm/6 am local time orbit at 600 km. This restricts OSIRIS sunlit observations to the Northern hemisphere in May, June, July and August, and the Southern hemisphere in November, December, January and February. Global coverage from 82°S to 82°N occurs on the months adjoining the equinoxes. OSIRIS measurements began November, 2001 and continue to the present. == Objectives == Stratospheric ozone science: To elucidate the geographical extent of, and mechanisms responsible for, ozone depletion in the "ozone hole" region and to study dilution effects and possible heterogeneous chemistry even outside of the polar regions due to sulphate aerosols. Coupling of atmospheric regions: To study some of the mechanisms that provide coupling between the upper and lower atmosphere, e.g., downward transport of NO with its effects on ozone photochemistry and the vertical exchange of minor species such as odd oxygen, CO, and H2O. == Instrument == The OSIRIS spectrograph


id: optical-payload-for-lasercomm-science-20260505-0
file: data/en.wikipedia.org/wiki/Optical_Payload_for_Lasercomm_Science-0.md
category: reference
title: Optical Payload for Lasercomm Science
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Optical_Payload_for_Lasercomm_Science
date_saved: 2026-05-05T09:45:42.173012+00:00
instance: kb-cron
parent: optical-payload-for-lasercomm-science-20260505-0
summary:
Optical PAyload for Lasercomm Science (OPALS) is a spacecraft communication instrument developed at the Jet Propulsion Laboratory that was tested on the International Space Station (ISS) from 18 April 2014 to 17 July 2014 to demonstrate the technology for laser communications systems between spacecraft and ground stations. The purpose of OPALS is to do research into replacing traditional radio-frequency (RF) communications which are currently used on spacecraft. This will allow spacecraft to increase the rate at which data is downlinked by 10 to 100 times. It also will have less error than RF communication. It launched from Cape Canaveral to the ISS on 18 April 2014 on a Falcon 9 SpaceX CRS-3 Dragon capsule resupply. The experiment used commercial products rather than space qualified components. == Science objectives == The goal of the OPALS mission was to demonstrate a downlink of a short video from space using laser communication. In doing so, the following was studied: Maintenance of an optical link between the ground and space with various environmental and operational conditions Processing of distorted data Procedure design for setting up the optical link What equipment is used for sending and receiving signal == Mission architecture == Communications and commands


id: orbiting-carbon-observatory-3-20260505-0
file: data/en.wikipedia.org/wiki/Orbiting_Carbon_Observatory_3-0.md
category: reference
title: Orbiting Carbon Observatory 3
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Orbiting_Carbon_Observatory_3
date_saved: 2026-05-05T09:45:43.336222+00:00
instance: kb-cron
parent: orbiting-carbon-observatory-3-20260505-0
summary:
The Orbiting Carbon Observatory-3 (OCO-3) is a NASA-JPL instrument designed to measure carbon dioxide in Earth's atmosphere. The instrument is mounted on the Japanese Experiment Module-Exposed Facility on board the International Space Station (ISS). OCO-3 was launched as part of CRS-17 on 4 May 2019 at 06:48 UTC. The nominal mission lifetime is ten years. OCO-3 was assembled using spare materials from the Orbiting Carbon Observatory-2 satellite. Because the OCO-3 instrument is similar to the OCO-2 instrument, it is expected to have similar performance with its measurements used to quantify CO2 to 1 ppm precision or better at 3 Hz. == History and timeline == 24 February 2009 - Orbiting Carbon Observatory was launched on a Taurus XL rocket but failed to achieve orbit when the fairing failed to separate from the satellite. 1 February 2010 - The 2010 President's budget included funding for development and re-flight of an OCO replacement. October 2010 - The Orbiting Carbon Observatory-2 project went into implementation phase. 2 July 2014 - OCO-2 was successfully launched from Vandenberg Air Force Base with a Delta II rocket. 2015 - Funding for the OCO-3 project cancelled. 22 December 2015 - OCO-3 project authorized to proceed. Funding was


id: planetary-fourier-spectrometer-20260505-0
file: data/en.wikipedia.org/wiki/Planetary_Fourier_Spectrometer-0.md
category: reference
title: Planetary Fourier Spectrometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Planetary_Fourier_Spectrometer
date_saved: 2026-05-05T09:45:44.525581+00:00
instance: kb-cron
parent: planetary-fourier-spectrometer-20260505-0
summary:
The Planetary Fourier Spectrometer (PFS) is an infrared spectrometer built by the Istituto Nazionale di Astrofisica (Italian National Institute for Astrophysics) along with the Istituto di Fisica dello spazio Interplanetario and the Consiglio Nazionale delle Ricerche (Italian National Research Council). The instrument is currently used by the European Space Agency on both the Mars Express Mission and the Venus Express Mission. It consists of four units which together weigh around 31.4 kg, including a pointing device, a power supply, a control unit, and an interferometer with electronics. The main objective of the instrument is to provide temperature profiles of Mars's carbon dioxide atmosphere, and to the study composition of the planet's atmosphere through the infrared radiation that is reflected and emitted by the planet. == Methane in the Martian atmosphere == In March 2004, Professor Vittorio Formisano, the researcher in charge of the Mars Express Planetary Fourier Spectrometer, announced the discovery of methane in the Martian atmosphere. However, methane cannot persist in the Martian atmosphere for more than a few hundred years since it can be broken down by sunlight. Thus, this discovery suggests that the methane is being continually replenished by some unidentified volcanic or geologic process, or that


id: plasma-instrument-for-magnetic-sounding-20260505-0
file: data/en.wikipedia.org/wiki/Plasma_Instrument_for_Magnetic_Sounding-0.md
category: reference
title: Plasma Instrument for Magnetic Sounding
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plasma_Instrument_for_Magnetic_Sounding
date_saved: 2026-05-05T09:45:45.712227+00:00
instance: kb-cron
parent: plasma-instrument-for-magnetic-sounding-20260505-0
summary:
The Plasma Instrument for Magnetic Sounding (PIMS) is a Faraday cup based instrument that will fly on board the Europa Clipper orbiter to explore Jupiter's moon Europa. PIMS will measure the plasma that populates Jupiter's magnetosphere and Europa's ionosphere. The principal investigator is Dr. Adrienn Luspay-Kuti, from the Johns Hopkins University Applied Physics Laboratory (APL). == Overview == The plasma in Jupiter's magnetosphere interacts with Europa's atmosphere. This interaction results in magnetic field perturbations. While understanding this plasma interaction is inherently interesting, it is also crucial for successful magnetic sounding Europa's subsurface ocean. The interaction of the Jovian magnetic field with Europa's subsurface ocean produces a magnetic induction signature that is used to determine the ice shell thickness, ocean depth, and ocean salinity of Europa's subsurface ocean. Separating the sources of magnetic field perturbations produces a better understanding of the ocean's properties. The Plasma Instrument for Magnetic Sounding (PIMS) is a Faraday cup-based instrument that will measure the plasma of Jupiter's magnetosphere and Europa's ionosphere. Such devices on spacecraft date back to Explorer 10 in 1961 and were used by the Voyager 1 spacecraft to study Jupiter's magnetosphere in 1979. == Science goals == The three science goals of PIMS


id: plasma-wave-instrument-20260505-0
file: data/en.wikipedia.org/wiki/Plasma_wave_instrument-0.md
category: reference
title: Plasma wave instrument
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plasma_wave_instrument
date_saved: 2026-05-05T09:45:46.896589+00:00
instance: kb-cron
parent: plasma-wave-instrument-20260505-0
summary:
A plasma wave instrument (PWI), also known as a plasma wave receiver, is a device capable of detecting vibrations in outer space plasma and transforming them into audible sound waves or air vibrations that can be heard by the human ear. This instrument was pioneered by then-University of Iowa physics professor, Donald Gurnett. Plasma wave instruments are commonly employed on space probes such as GEOTAIL, Polar, Voyager I and II (see Plasma Wave Subsystem), and Cassini–Huygens. == Operating principle == Vibrations in the audible frequency range are perceived by humans when air vibrates against their eardrum. Air, or some other vibrating medium such as water, is essential for sound perception by the human ear. Without a medium to transmit it, the sound produced by a source will not be heard by a human. There is no air in outer space, nor is there any other type of medium capable of transmitting vibrations from a source to a human ear. However, there are sources in outer space that vibrate at frequencies audible to humans if only there were some transmitting medium to carry those vibrations from the source to a human eardrum. One such source capable of vibrating at audible frequencies


id: plasma-wave-subsystem-20260505-0
file: data/en.wikipedia.org/wiki/Plasma_Wave_Subsystem-0.md
category: reference
title: Plasma Wave Subsystem
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plasma_Wave_Subsystem
date_saved: 2026-05-05T09:45:48.115930+00:00
instance: kb-cron
parent: plasma-wave-subsystem-20260505-0
summary:
Plasma Wave Subsystem (sometimes called Plasma Wave System), abbreviated PWS, is an instrument that is on board the Voyager 1 and Voyager 2 unmanned probes of the Voyager program. The device is 16 channel step frequency receiver and a low-frequency waveform receiver that can measure electron density. The PWS uses the two long antenna in a V-shape on the spacecraft, which are also used by another instrument on the spacecraft. The instrument recorded data about the Solar System's gas giants, and about the outer reaches of the Heliosphere, and beyond. In the 2010s, the PWS was used to play the "sounds of interstellar space" as the spacecraft can sample the local interstellar medium after they departed the Sun's heliosphere. The heliosphere is a region essentially under the influence of the Sun's solar wind, rather than the local interstellar environment, and is another way of understanding the Solar System in comparison to the objects gravitationally bound (e.g in orbit) around Earth's Sun. The PWS instrument plan was introduced in 1974 during the development of the Voyager program. It was hoped it would help increase understanding of wave particle interactions and record data on the magnetospheres of planets like Jupiter and Saturn.


id: pluto-energetic-particle-spectrometer-science-investigation-20260505-0
file: data/en.wikipedia.org/wiki/Pluto_Energetic_Particle_Spectrometer_Science_Investigation-0.md
category: reference
title: Pluto Energetic Particle Spectrometer Science Investigation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Pluto_Energetic_Particle_Spectrometer_Science_Investigation
date_saved: 2026-05-05T09:45:49.355754+00:00
instance: kb-cron
parent: pluto-energetic-particle-spectrometer-science-investigation-20260505-0
summary:
Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI), is an instrument on the New Horizons space probe to Pluto and beyond, it is designed to measure ions and electrons. Specifically, it is focused on measuring ions escaping from the atmosphere of Pluto during the 2015 flyby. It is one of seven major scientific instruments aboard the spacecraft. The spacecraft was launched in 2006, flew by Jupiter the following year, and went on to flyby Pluto in 2015 where PEPSSI was able to record and transmit back to Earth its planned data collections. PEPSSI is designed to help understand the rate of atmospheric loss from the atmosphere of Pluto into space, which is thought experience comet-like atmosphere loss into outer space. These ions blend in with the surrounding solar wind which passed by Pluto. During the flyby PEPSSI sent data back to Earth every day. During the journey to Pluto, PEPSSI was also used to record data about the interplanetary medium. Data about Jupiter and its magnetotail was also collected by PEPSSI during its 2007 flyby of that planet. Beyond Pluto and into the Kuiper belt, PEPSSI can be used to study how the solar wind interacts with interstellar wind, adding to


id: radar-for-europa-assessment-and-sounding-ocean-to-near-surface-20260505-0
file: data/en.wikipedia.org/wiki/Radar_for_Europa_Assessment_and_Sounding:_Ocean_to_Near-surface-0.md
category: reference
title: Radar for Europa Assessment and Sounding: Ocean to Near-surface
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Radar_for_Europa_Assessment_and_Sounding:_Ocean_to_Near-surface
date_saved: 2026-05-05T09:45:50.531916+00:00
instance: kb-cron
parent: radar-for-europa-assessment-and-sounding-ocean-to-near-surface-20260505-0
summary:
The Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) is a multi-frequency, multi-channel ice penetrating radar system that will be flown on board the Europa Clipper mission to Jupiter's moon Europa. REASON investigation will provide the first direct measurements of Europa's ice shell surface character and subsurface structure. == Overview == The REASON instrument makes innovative use of radar sounding, altimetry, reflectometry, plasma and particles analyses. These investigations will use a dual-frequency radar emitting HF (9 MHz) and VHF (60 MHz) with concurrent shallow and deep sounding. Both VHF and HF radiating elements are mounted on a single boom, reducing antenna mass. The mission plan also includes using REASON as a nadir altimeter capable of measuring tides to test ice shell and ocean hypotheses as well as characterizing roughness across the surface to identify potential landing sites for a future Europa Lander. The REASON instrument will also be able to spot pockets of water within the ice shell that could serve as a passageway for chemicals on the moon's surface to the ocean below — an environment where life could potentially develop. The instrument was developed by the Jackson School of Geosciences, and its Principal Investigator is Donald


id: radio-science-subsystem-20260505-0
file: data/en.wikipedia.org/wiki/Radio_science_subsystem-0.md
category: reference
title: Radio science subsystem
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Radio_science_subsystem
date_saved: 2026-05-05T09:45:51.728266+00:00
instance: kb-cron
parent: radio-science-subsystem-20260505-0
summary:
A radio science subsystem (RSS) is a subsystem placed on board a spacecraft for radio science purposes. == Function of the RSS == The RSS uses radio signals to probe a medium such as a planetary atmosphere. The spacecraft transmits a highly stable signal to ground stations, receives such a signal from ground stations, or both. Since the transmitted signal parameters are accurately known to the receiver, any changes to these parameters are attributable to the propagation medium or to the relative motion of the spacecraft and ground station. The RSS is usually not a separate instrument; its functions are usually "piggybacked" on the existing telecommunications subsystem. More advanced systems use multiple antennas with orthogonal polarizations. == Applications == Radio science is commonly used to determine the gravity field of a moon or planet by observing Doppler shift. This requires a highly stable oscillator on the spacecraft, or more commonly a "2-way coherent" transponder that phase locks the transmitted signal frequency to a rational multiple of a received uplink signal that usually also carries spacecraft commands. Another common radio science observation is in radio occultation, performed as a spacecraft is occulted by a planetary body. As the spacecraft moves behind


id: ralph-new-horizons-20260505-0
file: data/en.wikipedia.org/wiki/Ralph_(New_Horizons)-0.md
category: reference
title: Ralph (New Horizons)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ralph_(New_Horizons)
date_saved: 2026-05-05T09:45:52.956371+00:00
instance: kb-cron
parent: ralph-new-horizons-20260505-0
summary:
Ralph is a science instrument aboard the robotic New Horizons spacecraft, which was launched in 2006. Ralph is a visible and infrared imager and spectrometer to provide maps of relevant astronomical targets based on data from that hardware. Ralph has two major subinstruments, LEISA and MVIC. MVIC stands for Multispectral Visible Imaging Camera and is a color imaging device, while LEISA originally stood for Linear Etalon Imaging Spectral Array and is an infrared imaging spectrometer for spaceflight. LEISA observes 250 discrete wavelengths of infrared light from 1.25 to 2.5 micrometers. MVIC is a pushbroom scanner type of design with seven channels, including red, blue, near-infrared (NIR), and methane. == Overview == Ralph is one of seven major instruments aboard New Horizons which was launched in 2006 and flew by the dwarf planet Pluto in 2015. At Pluto, Ralph enables the observation of many aspects including: geology of Pluto form structure surface composition surface temperature Ralph and Alice were used to characterize the atmosphere of Pluto in 2015. Ralph was previously used to observe the planet Jupiter and its moons in 2006 and in 2007 when it flew-by en route out of the Solar System and past Pluto. Observations of Jupiter


id: raman-laser-spectrometer-20260505-0
file: data/en.wikipedia.org/wiki/Raman_Laser_Spectrometer-0.md
category: reference
title: Raman Laser Spectrometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Raman_Laser_Spectrometer
date_saved: 2026-05-05T09:45:54.156293+00:00
instance: kb-cron
parent: raman-laser-spectrometer-20260505-0
summary:
Raman Laser Spectrometer (RLS) is a miniature Raman spectrometer that is part of the science payload on board the European Space Agency's Rosalind Franklin rover, tasked to search for biosignatures and biomarkers on Mars. The rover is planned to be launched not earlier than 2028 and land on Mars in 2029. Raman spectroscopy is a technique employed to identify mineral phases produced by water-related processes. RLS will help to identify organic compounds and search for microbial life by identifying the mineral products and indicators of biologic activities. RLS will provide geological and mineralogical context information that will be scientifically cross-correlated with that obtained by other instruments. == Overview == Raman spectroscopy is sensitive to the composition and structure of any organic compound, making it a powerful tool for the definitive identification and characterisation of biomarkers, and providing direct information of potential biosignatures of past microbial life on Mars. This instrument will also provide general mineralogical information for igneous, metamorphous, and sedimentary processes. RST will also correlate its spectral information with other spectroscopic and imaging instruments such as the Infrared Spectrometer and MicrOmega-IR. This will be the first Raman analyser to be deployed for a planetary exploration. The first version for


id: reentry-breakup-recorder-20260505-0
file: data/en.wikipedia.org/wiki/Reentry_Breakup_Recorder-0.md
category: reference
title: Reentry Breakup Recorder
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Reentry_Breakup_Recorder
date_saved: 2026-05-05T09:45:55.347164+00:00
instance: kb-cron
parent: reentry-breakup-recorder-20260505-0
summary:
A Reentry Breakup Recorder (REBR) is a device that is designed to be placed aboard a spacecraft to record pertinent data when the spacecraft (intentionally) breaks up as it re-enters Earth's atmosphere. The device records data regarding the thermal, acceleration, rotational and other stresses the vehicle is subject to. In the final stages it transmits the data back to a laboratory before it is destroyed when it hits the surface. == History == Two REBRs were launched in January 2011 on the Japanese Kounotori 2 transfer vehicle. One recorded the subsequent re-entry of that vehicle, and the other was placed aboard the Johannes Kepler ATV, which reentered Earth's atmosphere on 21 June 2011. The Kounotori 2 vehicle re-entered on 30 March 2011. Its REBR successfully collected and returned its data; it survived the impact with the ocean and while floating continued to transmit. It took between 6 and 8 weeks to analyze the data. The second unit was intended to collect data during the reentry of the Johannes Kepler ATV (ATV-2); however the device failed to make contact after reentry and consequently no data was retrieved. Two other units were used successfully for Kounotori 3 for its reentry on September


id: rex-new-horizons-20260505-0
file: data/en.wikipedia.org/wiki/REX_(New_Horizons)-0.md
category: reference
title: REX (New Horizons)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/REX_(New_Horizons)
date_saved: 2026-05-05T09:45:56.561398+00:00
instance: kb-cron
parent: rex-new-horizons-20260505-0
summary:
REX or Radio Science Experiment is an experiment on the New Horizons space probe to measure properties of the atmosphere of Pluto during the 2015 flyby. == Experiment == Experiment was designed with several goals including determination of pressure and temperature of Plutonian atmosphere, measurements of a possible ionosphere of Pluto and Charon, recording thermal emission temperatures, and taking more accurate chord lengths of Charon and Pluto. To accomplish the goals, as the spacecraft passed by Pluto, it was placed on a path that took it behind the dwarf planet in relation to the Earth, where radio signals from the flyby spacecraft passed through its atmosphere allowing various properties to be determined. REX also took measurements of the atmospheric conditions at Pluto's moon Charon as part of the mission. REX uses an ultrastable oscillator, various electronics, and radio hardware aboard the New Horizons spacecraft. REX uses the X-band radio uplink on the spacecraft. REX hardware weighs 160g (0.16 kg) and consumes 1.6 watts of spacecraft electrical power. It also makes use of other NH hardware, overall key hardware components for REX include: high-gain antenna low-noise X-band receiver ultrastable oscillator To take the measurements, REX communicates with the Deep Space Network


id: rock-abrasion-tool-20260505-0
file: data/en.wikipedia.org/wiki/Rock_Abrasion_Tool-0.md
category: reference
title: Rock Abrasion Tool
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Rock_Abrasion_Tool
date_saved: 2026-05-05T09:45:57.773704+00:00
instance: kb-cron
parent: rock-abrasion-tool-20260505-0
summary:
The Rock Abrasion Tool (RAT) is a grinding and brushing installation on NASA’s twin Mars Exploration Rovers, Spirit (MER-A) and Opportunity (MER-B), which landed on Mars in January 2004. It was designed, developed and continues to be operated by Honeybee Robotics LTD, a developer of specialized robots, automated technologies and related systems. The RAT was the first machine to gain access to the interior of rocks on another planet. The RAT has a mass of 0.685 kilograms (1.51 pounds), is 7 cm (3 in) in diameter and 10 cm (3.9 in) long, about the size of a soda can. It uses a diamond dust and resin wheel spinning at 3000 rpm to drill a 45 mm diameter by 5 mm deep bore hole in martian rocks. The RAT then uses two brushes to sweep dust from the bore holes for closer scientific inspection. Its average power consumption is 30 watts. There are five other instruments aboard both rovers, these are the Pancam (a camera), Mini-TES (an infrared spectrometer) for sensing targets at a distance, a microscopic imager, a Mössbauer spectrometer and an alpha particle X-ray spectrometer. The RAT provides these instruments with a smooth, clean surface from which they make


id: rotation-and-interior-structure-experiment-20260505-0
file: data/en.wikipedia.org/wiki/Rotation_and_Interior_Structure_Experiment-0.md
category: reference
title: Rotation and Interior Structure Experiment
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Rotation_and_Interior_Structure_Experiment
date_saved: 2026-05-05T09:45:58.982975+00:00
instance: kb-cron
parent: rotation-and-interior-structure-experiment-20260505-0
summary:
Rotation and Interior Structure Experiment (RISE) is a radio science experiment onboard InSight Mars lander that will use the spacecraft communication system to provide precise measurements of Mars' rotation and wobble. RISE precisely tracks the location of the lander to measure how much Mars's axis wobbles as it orbits the Sun. These observations will provide new constraints on the core radius and help determine whether the core of Mars is mostly liquid, and which other elements, besides iron, may be present. This study will also help scientists understand why Mars's magnetic field is so weak, as compared to Earth's. The mission launched on 5 May 2018 and landed on the surface of Mars at Elysium Planitia on 26 November 2018. == Overview == The Principal Investigator for RISE is William Folkner of JPL, who led the 1997 investigation of Mars's core using the radio link between Earth and NASA's Mars Pathfinder. RISE uses the spacecraft's radio connection with Earth to assess perturbations of Mars's rotation axis to within 10 centimeters. These measurements can provide information about the size and composition of Mars's core. The radio science equipment is largely the same as used for the Mars Exploration Rover mission, and


id: sbuv-2-20260505-0
file: data/en.wikipedia.org/wiki/SBUV/2-0.md
category: reference
title: SBUV/2
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/SBUV/2
date_saved: 2026-05-05T09:46:00.154245+00:00
instance: kb-cron
parent: sbuv-2-20260505-0
summary:
The Solar Backscatter Ultraviolet Radiometer, or SBUV/2, is a series of operational remote sensors on NOAA weather satellites in Sun-synchronous orbits which have been providing global measurements of stratospheric total ozone, as well as ozone profiles, since March 1985. The SBUV/2 instruments were developed from the SBUV experiment flown on the Nimbus-7 spacecraft which improved on the design of the original BUV instrument on Nimbus-4. These are nadir viewing radiometric instruments operating at mid to near UV wavelengths. SBUV/2 data sets overlap with data from SBUV and TOMS instruments on the Nimbus-7 spacecraft. These extensive data sets (January 1979 to the present) measure the density and vertical distribution of ozone in the Earth's atmosphere from six to 30 miles. SBUV/2 looks down at the Earth's atmosphere and the reflected sunlight at wavelengths characteristic of ozone. The SBUV/2 wavelength "channels" range from 252 nanometer (nm) to 340 nm. Ozone is measured as a ratio of sunlight incident on the atmosphere to the amount of sunlight scattered back into space. From this information, the total ozone between the instrument and the ground can be calculated. The SBUV/2 measures solar irradiance and Earth radiance (backscattered solar energy) in the near ultraviolet spectrum (160


id: seismic-experiment-for-interior-structure-20260505-0
file: data/en.wikipedia.org/wiki/Seismic_Experiment_for_Interior_Structure-0.md
category: reference
title: Seismic Experiment for Interior Structure
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Seismic_Experiment_for_Interior_Structure
date_saved: 2026-05-05T09:46:01.421738+00:00
instance: kb-cron
parent: seismic-experiment-for-interior-structure-20260505-0
summary:
The Seismic Experiment for Interior Structure (SEIS) is a seismometer and the primary scientific instrument on board the InSight Mars lander launched on 5 May 2018 for a landing on 26 November 2018; the instrument was deployed to the surface of Mars on 19 December. SEIS is expected to provide seismic measurements of marsquakes, enabling researchers to develop 3D structure maps of the deep interior. Better understanding the internal structure of Mars will lead to better understanding of the Earth, Moon, and rocky planetary bodies in general. SEIS detected marsquakes in Cerberus Fossae in 2019. On 24 December 2021, the seismometer for the InSight mission on Mars detected a large seismic event with a distinct signature. The event was caused by a meteor impact on the surface of Mars, which was confirmed by satellite observations of a newly formed 150-meter crater. As of 21 December 2022, which marks the official end of the InSight mission, SEIS has detected a total of 1319 marsquakes. == Overview == Mars flybys and landings to gather scientific data have been conducted since the 1960s, but quality seismological studies – which would provide detailed information about the interior of Mars – have yet to be


id: shuttle-radar-topography-mission-20260505-0
file: data/en.wikipedia.org/wiki/Shuttle_Radar_Topography_Mission-0.md
category: reference
title: Shuttle Radar Topography Mission
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Shuttle_Radar_Topography_Mission
date_saved: 2026-05-05T09:46:02.602314+00:00
instance: kb-cron
parent: shuttle-radar-topography-mission-20260505-0
summary:
The Shuttle Radar Topography Mission (SRTM) is an international research effort that obtained digital elevation models on a near-global scale from 56°S to 60°N, to generate the most complete high-resolution digital topographic database of Earth prior to the release of the ASTER GDEM in 2009. The technique employed for generating topographic data by radar is known as interferometric synthetic aperture radar. It flew onboard the 11-day STS-99 mission in February 2000. Intermap Technologies was the prime contractor for processing the interferometric synthetic aperture radar data. The elevation models derived from the SRTM data are used in geographic information systems. They can be downloaded freely over the Internet, and their file format (.hgt) is widely supported. The Shuttle Radar Topography Mission is an international project spearheaded by the U.S. National Geospatial-Intelligence Agency (NGA), an agency of the U.S. Department of Defense, and the U.S. National Aeronautics and Space Administration (NASA). == Mission and instrument == The mission consists of an interferometric synthetic aperture radar system based on the older Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR), previously used on the Shuttle in 1994. It features two antennas, a critical change from SIR-C/X-SAR, allowing single-pass interferometry. One antenna was located in the


id: shuttle-radar-topography-mission-20260505-1
file: data/en.wikipedia.org/wiki/Shuttle_Radar_Topography_Mission-1.md
category: reference
title: Shuttle Radar Topography Mission
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Shuttle_Radar_Topography_Mission
date_saved: 2026-05-05T09:46:02.602314+00:00
instance: kb-cron
parent: shuttle-radar-topography-mission-20260505-0
summary:
==== Highest resolution global release ==== SRTM-GL1 is a void-filled digital elevation model with 1-arcsecond (30 meter) resolution, or alternatively a high-resolution version of "SRTM version 3". It was released in 2014. It is available from the United States Geological Survey web site and the NASA data catalog. The United States Government announced on September 23, 2014 over a United Nations Climate Summit that the highest possible resolution of global topographic data derived from the SRTM mission will be released to public. Before the end of the same year, a 1-arc second global digital elevation model (30 meters) was released. Most parts of the world have been covered by this dataset ranging from 54°S to 60°N latitude except for the Middle East and North Africa area. Missing coverage of the Middle East was completed in August 2015. Jonathan de Ferranti published a short review of the new SRTM-GL1 data product in 2015. The effective resolution is about 50 metres, compared with 100 meters for versions 1 and 2 of ASTER GDEM. Voids remain around Mount Everest and the Swiss/Italian Matterhorn. There are some artificial details (bumps and pits), but at a lower amplitude than ASTER GDEM. === Third-party derivatives ===


id: signs-of-life-detector-20260505-0
file: data/en.wikipedia.org/wiki/Signs_Of_LIfe_Detector-0.md
category: reference
title: Signs Of LIfe Detector
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Signs_Of_LIfe_Detector
date_saved: 2026-05-05T09:46:03.796986+00:00
instance: kb-cron
parent: signs-of-life-detector-20260505-0
summary:
Signs Of LIfe Detector (SOLID) is an analytical instrument under development to detect extraterrestrial life in the form of organic biosignatures obtained from a core drill during planetary exploration. The instrument is based on fluorescent immunoassays and it is being developed by the Spanish Astrobiology Center (CAB) in collaboration with the NASA Astrobiology Institute. SOLID is currently undergoing testing for use in astrobiology space missions that search for common biomolecules that may indicate the presence of extraterrestrial life, past or present. The system was validated in field tests and engineers are looking into ways to refine the method and miniaturize the instrument further. == Science background == Modern astrobiology inquiry has emphasized the search for water on Mars, chemical biosignatures in the permafrost, soil and rocks at the planet's surface, and even biomarker gases in the atmosphere that may give away the presence of past or present life. The detection of preserved organic molecules of unambiguous biological origin is fundamental for the confirmation of present or past life, but the 1976 Viking lander biological experiments failed to detect organics on Mars, and it is suspected it was because of the combined effects of heat applied during analysis and the unexpected


id: sir-2-20260505-0
file: data/en.wikipedia.org/wiki/SIR-2-0.md
category: reference
title: SIR-2
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/SIR-2
date_saved: 2026-05-05T09:46:05.007315+00:00
instance: kb-cron
parent: sir-2-20260505-0
summary:
The SIR-2 instrument is a redesigned, highly compact, monolithic grating, near infrared spectrometer chosen to be a payload on the Indian Chandrayaan-1 satellite. It is an ESA project, and is built by Max Planck Institute for Solar System Research, Polish Academy of Sciences and University of Bergen. == Mission == The mission of the instrument is to map the lunar surface in the near infrared spectrum from 0.9 - 2.4 μm with an unprecedented resolution of 6 nm. The purpose of this is to obtain information on the mineral composition of the moon, which in turn will help getting insight into a number of questions: What is the cause of the global asymmetry of the moon, which on the far side has a thicker crust and lacks the Mare structures which are characteristic for the near side? What was the early thermal evolution of the moon? What is the vertical and lateral structure of the lunar crust and how did it develop? What is the composition and structure of the lunar mantle? Why is the moon different from other planets and how do planets work in terms of surface processes, heat transfer, and geologic evolution? Are the Apollo geophysical measurements


id: solar-x-ray-imager-20260505-0
file: data/en.wikipedia.org/wiki/Solar_X-ray_Imager-0.md
category: reference
title: Solar X-ray Imager
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Solar_X-ray_Imager
date_saved: 2026-05-05T09:46:06.212667+00:00
instance: kb-cron
parent: solar-x-ray-imager-20260505-0
summary:
Solar X-ray Imager (SXI) are full-disc X-ray instruments observing the Sun aboard GOES satellites. The SXI on GOES 12 was the first of its kind and allows the U.S. NOAA to better monitor and predict space weather. == Operation == The Solar X-ray Imager aboard the GOES 12, GOES 13, GOES 14, and GOES 15 NOAA weather satellites is used for early detection of solar flares, coronal mass ejections (CMEs), and space phenomena that impact human spaceflight and military and commercial satellite communications. The Solar X-ray Imager was the first X-ray telescope to take a "full-disk" image of the Sun, providing forecasters with the ability to detect solar storms and real-time solar forecasting by the Space Weather Prediction Center (SWPC). == Imagery == The SXI aboard GOES 12 is a Wolter Type I (Wolter telescope) grazing incidence X-ray telescope designed to record coronal images in continuous sequence at 1-minute intervals. The Solar X-ray Imager obtains images at multiple wavelengths on the electromagnetic spectrum from 6 to 60 angstrom units (Å). The imagery obtained by the XSI and XRS on GOES 12 allowed forecasters to see space phenomena such as coronal holes, whose geomagnetic and proton storms impact electrical grid systems


id: spaceborne-imaging-radar-20260505-0
file: data/en.wikipedia.org/wiki/Spaceborne_Imaging_Radar-0.md
category: reference
title: Spaceborne Imaging Radar
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Spaceborne_Imaging_Radar
date_saved: 2026-05-05T09:46:07.354704+00:00
instance: kb-cron
parent: spaceborne-imaging-radar-20260505-0
summary:
The Spaceborne Imaging Radar (SIR) – full name 'Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR)', is a synthetic aperture radar which flew on two separate shuttle missions. Once from the Space Shuttle Endeavour in April 1994 on (STS-59) and again in October 1994 on (STS-68). The radar was run by NASA's Space Radar Laboratory. SIR utilizes 3 radar frequencies: L band (24 cm wavelength), C band (6 cm) and X band (3 cm), allowing for study of geology, hydrology, ecology and oceanography. Comparing radar images to data collected by teams of people on the ground as well as aircraft and ships using simultaneous measurements of vegetation, soil moisture, sea state, snow and weather conditions during each flight. The imaging radar was able to take images anytime regardless of clouds cover. The Radar-C system was built and operated by NASA's Jet Propulsion Laboratory (JPL). The mission was a joint work of NASA with the German and Italian space agencies. Each of the week long mission scanned about 50 million square kilometers of the Earth's surface, (19.3 million square miles). The SIR mission revealed hidden river channels in the Sahara Desert indicating significant climate change in the past. SIR was also used


id: spacecraft-atmosphere-monitor-20260505-0
file: data/en.wikipedia.org/wiki/Spacecraft_Atmosphere_Monitor-0.md
category: reference
title: Spacecraft Atmosphere Monitor
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Spacecraft_Atmosphere_Monitor
date_saved: 2026-05-05T09:46:08.543451+00:00
instance: kb-cron
parent: spacecraft-atmosphere-monitor-20260505-0
summary:
The Spacecraft Atmosphere Monitor (SCRAM) is a highly compact gas chromatograph mass spectrometer (GCMS) instrument built by JPL that is a technology demonstration on the International Space Station for monitoring the cabin atmosphere in human spacecraft. SCRAM measures both the major constituents (e.g. nitrogen, oxygen, and carbon dioxide) and trace parts per billion volatile chemicals (e.g. benzene, ethanol, siloxanes) in the spacecraft cabin atmosphere to ensure the health of the astronauts. SCRAM has a total mass of 9.5 kg and uses 40 W (nominal) during operation. SCRAM is an advanced technology demonstration that can be employed on future crewed flight missions, like in the Artemis program and the Orion spacecraft. It was launched to ISS on a Dragon spacecraft on July 25, 2019, and began continuous operations on July 29, 2019. SCRAM was returned to earth aboard SpaceX-25 on Jan. 24, 2022 after almost two years of continuous operations aboard the ISS, exceeding its design lifetime goal of one year. The instrument was returned to JPL on Feb. 15, 2022. This first SCRAM instrument will be refurbished and be flown, along with a second SCRAM unit (SCRAM-2), to ISS in late 2022. The two instruments operating at the same time


id: special-sensor-microwave-imager-20260505-0
file: data/en.wikipedia.org/wiki/Special_sensor_microwave/imager-0.md
category: reference
title: Special sensor microwave/imager
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Special_sensor_microwave/imager
date_saved: 2026-05-05T09:46:09.711725+00:00
instance: kb-cron
parent: special-sensor-microwave-imager-20260505-0
summary:
The Special Sensor Microwave/Imager (SSM/I) is a seven-channel, four-frequency, linearly polarized passive microwave radiometer system. It is flown on board the United States Air Force Defense Meteorological Satellite Program (DMSP) Block 5D-2 satellites. The instrument measures surface/atmospheric microwave brightness temperatures (TBs) at 19.35, 22.235, 37.0 and 85.5 GHz. The four frequencies are sampled in both horizontal and vertical polarizations, except the 22 GHz which is sampled in the vertical only. The SSM/I has been a very successful instrument, superseding the across-track and Dicke radiometer designs of previous systems. Its combination of constant-angle rotary-scanning and total power radiometer design has become standard for passive microwave imagers, e.g. TRMM Microwave Imager, AMSR. Its predecessor, the Scanning Multichannel Microwave Radiometer (SMMR), provided similar information. Its successor, the Special Sensor Microwave Imager / Sounder (SSMIS), is an enhanced eleven-channel, eight-frequency system. == Products == Along with its predecessor SMMR, the SSM/I contributes to an archive of global passive microwave products from late 1978 to present. Information within the SSM/I TBs measurements allow the retrieval of four important meteorological parameters over the ocean: near-surface wind speed (note scalar not vector), total columnar water vapor, total columnar cloud liquid water (liquid water path) and precipitation. Accurate


id: spectrometer-telescope-for-imaging-x-rays-20260505-0
file: data/en.wikipedia.org/wiki/Spectrometer_Telescope_for_Imaging_X-rays-0.md
category: reference
title: Spectrometer Telescope for Imaging X-rays
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Spectrometer_Telescope_for_Imaging_X-rays
date_saved: 2026-05-05T09:46:10.877832+00:00
instance: kb-cron
parent: spectrometer-telescope-for-imaging-x-rays-20260505-0
summary:
The Spectrometer Telescope for Imaging X-rays (STIX) is one of the 10 instruments that are part of the scientific payload for the ESA Solar Orbiter mission launched in 2020. The STIX instrument is an X-ray imaging spectrometer, whose purpose is to study the extremely hot solar plasma and the high-energy electrons accelerated during a solar flare. It can detect X-rays from 4 to 150 keV and exploits an indirect imaging technique based on the moiré effect, to produce images with few arcsec angular resolution in any given energy range. The instrument has been developed by an international collaboration led by the University of Applied Sciences Northwestern Switzerland. == External links == STIX Data Center The spectrometer/telescope for imaging X-rays on board the ESA Solar Orbiter spacecraft ESA Solar Orbiter


id: ssmis-20260505-0
file: data/en.wikipedia.org/wiki/SSMIS-0.md
category: reference
title: SSMIS
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/SSMIS
date_saved: 2026-05-05T09:46:12.001520+00:00
instance: kb-cron
parent: ssmis-20260505-0
summary:
The Special Sensor Microwave Imager / Sounder (SSMIS) is a 24-channel, 21-frequency, linearly polarized passive microwave radiometer system. The instrument is flown on board the United States Air Force Defense Meteorological Satellite Program (DMSP) F-16, F-17, F-18 and F-19 satellites, which were launched in October 2003, November 2006, October 2009, and April 2014, respectively. It is the successor to the Special Sensor Microwave/Imager (SSM/I). The SSMIS on the F19 satellite stopped producing useful data in February 2016. The Department of Defense announced it would cut off access to SSMIS data useful for calculating depth of sea ice and location of hurricanes, as of July 31, 2025. In late July 2025, the Department of Defense announced it will keep the SSMIS data flowing until the sensor fails or the program formally ends in September 2026. == Instrument characteristics == The SSMIS sensor is a passive conically scanning microwave radiometer that combines and extends the current imaging and sounding capabilities of three previously separate DMSP microwave sensors: the SSM/T-1 temperature sounder, the SSMI/T- 2 moisture sounder, and the SSM/I. The SSMIS instrument measures microwave energy at 24 discrete frequencies from 19 to 183 GHz with a swath width of 1700 km. The


id: surface-dust-analyser-20260505-0
file: data/en.wikipedia.org/wiki/Surface_Dust_Analyser-0.md
category: reference
title: Surface Dust Analyser
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Surface_Dust_Analyser
date_saved: 2026-05-05T09:46:13.209747+00:00
instance: kb-cron
parent: surface-dust-analyser-20260505-0
summary:
The SUrface Dust Analyzer (SUDA) is a time-of-flight mass spectrometer of reflectron-type that employs impact ionization and is optimised for a high mass resolution. The instrument was selected in May 2015 to fly on board the Europa Clipper mission which was sent to Jupiter's moon Europa in October, 2024. This instrument will measure the composition of small, solid particles ejected from Europa, providing the opportunity to directly sample the surface and potential plumes on low-altitude flybys. Europa's internal liquid water ocean has been identified as one of the locations in the Solar System that may offer habitable environments to microbial extraterrestrial life. == Overview == The basic idea of compositional mapping is that moons without an atmosphere are surrounded by clouds of dust particles released from their surfaces by meteoroid bombardment. The ejected particles can be sampled and their composition analyzed from orbit or during a spacecraft flyby. Since these grains are direct samples from the moons' icy surfaces, determination of their composition will help to define and constrain the geological activities on and below the moons' surface, the exchange processes with the deeper interior, and assess its internal ocean habitability potential. The instrument is capable of identifying traces of


id: swap-instrument-20260505-0
file: data/en.wikipedia.org/wiki/SWAP_(instrument)-0.md
category: reference
title: SWAP (instrument)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/SWAP_(instrument)
date_saved: 2026-05-05T09:46:15.034710+00:00
instance: kb-cron
parent: swap-instrument-20260505-0
summary:
The Sun Watcher using Active Pixel System Detector and Image Processing (SWAP) telescope is a compact extreme-ultraviolet (EUV) imager on board the PROBA-2 mission. SWAP provides images of the solar corona at a temperature of roughly 1 million degrees. the instrument was built upon the heritage of the Extreme ultraviolet Imaging Telescope (EIT) which monitored the solar corona from the Solar and Heliospheric Observatory from 1996 until after the launch of the Solar Dynamics Observatory in 2010. SWAP's coronal mass ejection (CME) watch program has collected images at an improved image cadence (typically 1 image every few minutes) since the PROBA-2 launch in 2009. These events include EIT waves (global waves propagating across the solar disc from the CME eruption site), EUV dimming regions (transient coronal holes from where the CME has lifted off), filament instabilities (a specific type of flickering during the rise of a filament). SWAP's EUV images of the corona routinely extend beyond 2 solar radii from the surface of the Sun, much further than was thought possible before the mission was launched. This led to the discovery, in 2021 by Seaton et al. using the SUVI instrument on board NOAA's GOES satellite, that the extended solar


id: swap-new-horizons-20260505-0
file: data/en.wikipedia.org/wiki/SWAP_(New_Horizons)-0.md
category: reference
title: SWAP (New Horizons)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/SWAP_(New_Horizons)
date_saved: 2026-05-05T09:46:16.200916+00:00
instance: kb-cron
parent: swap-new-horizons-20260505-0
summary:
SWAP (solar wind around Pluto) is a science instrument aboard the unmanned New Horizons space probe, which was designed to fly by dwarf planet Pluto. SWAP was designed to record solar wind en route, at, and beyond Pluto. At Pluto, SWAP's purpose was to record the relationship between the solarwind and ions and/or material entering space from the atmosphere of Pluto. == Background == The atmosphere of Pluto was discovered in 1988, but it remained enigmatic and it was hard to understand an atmosphere existing in such low temperatures (45 K, −230 °C, −380 °F). One of the ideas about Pluto is atmospheric loss, with Pluto being compared to losses from comets. The idea of atmospheric loss was suggested in 1980, even before the atmosphere was discovered. One idea is the photoionization of escaping neutral particles might alter the flow solar wind around the dwarf planet. The atmosphere was known to be very tenuous compared to Earth, and one of the questions was how the gases were interacting with the solar wind and sunlight, likewise weaker at Pluto's orbit than at Earth's. One of the ideas was that Pluto's atmosphere would be stripped away by the solar wind over time.


id: sweap-20260505-0
file: data/en.wikipedia.org/wiki/SWEAP-0.md
category: reference
title: SWEAP
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/SWEAP
date_saved: 2026-05-05T09:46:17.401031+00:00
instance: kb-cron
parent: sweap-20260505-0
summary:
The Solar Wind Electrons Alphas and Protons (SWEAP) is an instrument on the Parker Solar Probe, designed for an unmanned mission to the Sun's outer corona. The Parker Solar Probe was launched by a Delta IV Heavy on 12 August 2018 from Cape Canaveral, Florida. SWEAP includes two types of instruments: the Solar Probe Cup (SPC) and Solar Probe Analyzers (SPAN). SWEAP has four sensors overall, and is designed to take measurements of solar wind including electrons, ions of hydrogen (protons), and helium (the main components of solar wind and the coronal plasma). == Background == Scientists studying emission spectra of the Sun's corona during total solar eclipses thought they had found the presence of a new element they called "coronium." In the late 1930s, Walter Grotrian and Bengt Edlén postulated instead that these spectra were from highly ionized known elements, particularly iron. Since the levels of ionization they proposed required temperatures in the millions of Kelvins, this idea was initially not accepted as those temperatures were far higher than the actual surface of the Sun. This disparity was thought impossible as the corona should be cooler than the Sun, given that it lacks any apparent heat source of its


id: tagsam-20260505-0
file: data/en.wikipedia.org/wiki/TAGSAM-0.md
category: reference
title: TAGSAM
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/TAGSAM
date_saved: 2026-05-05T09:46:18.613929+00:00
instance: kb-cron
parent: tagsam-20260505-0
summary:
TAGSAM or Touch-and-Go Sample Acquisition Mechanism is a robotic arm on the OSIRIS-REx space probe designed and used for collecting a sample from asteroid 101955 Bennu. OSIRIS-REx was launched in 2016. It arrived at asteroid Bennu in December 2018, and began scientific studies. It collected a sample of the material making up the surface of Bennu in 2020 and returned it to Earth in 2023. == Overview == TAGSAM is a robotic arm attached to the main body of the spacecraft that collects a sample from the asteroid, and puts the samples into the Earth return vehicle. Bennu is about 500 meters in diameter and has very low gravity, so the arm must perform the collection in near zero gravity, yet still contend with some gravitational forces from the asteroid. One issue with small asteroids is their unique gravitational environment, and Bennu became the smallest body orbited by a spacecraft. TAGSAM was designed to take up to three samples from the asteroid, although in the event the first sample was so large no other samples were attempted. The collection head was filled using a nitrogen gas injection that stired up the regolith. The arm is about 11 feet (3.4 meters)


id: temperature-and-winds-for-insight-20260505-0
file: data/en.wikipedia.org/wiki/Temperature_and_Winds_for_InSight-0.md
category: reference
title: Temperature and Winds for InSight
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Temperature_and_Winds_for_InSight
date_saved: 2026-05-05T09:46:19.743594+00:00
instance: kb-cron
parent: temperature-and-winds-for-insight-20260505-0
summary:
Temperature and Winds for InSight (TWINS) is a NASA meteorological suite of instruments on board the InSight lander that landed on Mars on 26 November 2018. TWINS provides continuous wind and air temperature measurements to help understand the seismic data from the Seismic Experiment for Interior Structure (SEIS) instrument. The instruments were developed by the Spanish Astrobiology Center at Madrid, Spain. == Overview == TWINS is based on the heritage from REMS (Rover Environmental Monitoring Station) on board the Curiosity rover, with enhanced performances in terms of dynamic range and resolution. TWINS provides continuous wind and air temperature measurements to help understand the seismic data from the SEIS instrument. While probing the internal structure of Mars is the primary scientific goal of the InSight mission, atmospheric science remains a key science objective. InSight will provide a continuous and higher-frequency record of pressure, air temperature and winds at the surface of Mars than previous in situ missions. The sensors include thermometers, and an anemometer to measure wind speed and direction twice per second. Additional sensors are the InSight FluxGate (IFG) magnetometer provided by University of California, Los Angeles (UCLA) to measure the direction and magnitude of magnetic fields such as those


id: thermal-emission-spectrometer-20260505-0
file: data/en.wikipedia.org/wiki/Thermal_Emission_Spectrometer-0.md
category: reference
title: Thermal Emission Spectrometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Thermal_Emission_Spectrometer
date_saved: 2026-05-05T09:46:20.917037+00:00
instance: kb-cron
parent: thermal-emission-spectrometer-20260505-0
summary:
The Thermal Emission Spectrometer (TES) was an instrument on board Mars Global Surveyor. TES collected two types of data, hyperspectral thermal infrared data from 6 to 50 micrometres (μm) and bolometric visible-near infrared (0.3 to 2.9 μm) measurements. TES had six detectors arranged in a 2x3 array, and each detector had a field of view of approximately 3 × 6 km on the surface of Mars. The TES instrument used the natural harmonic vibrations of the chemical bonds in materials to determine the composition of gases, liquids, and solids. TES identified a large (30,000 square-kilometer) area that contained the mineral olivine. Olivine was found in the Nili Fossae formation. It is thought that the ancient impact that created the Isidis basin resulted in faults that exposed the olivine. Olivine is present in many mafic volcanic rocks. In the presence of water it weathers into minerals such as goethite, chlorite, smectite, maghemite, and hematite. Olivine was also discovered in many other small outcrops within 60 degrees north and south of the equator. Olivine has also been found in the SNC (shergottite, nakhlite, and chassigny) meteorites that are generally accepted to have come from Mars. Later studies found the olivine-rich rocks to


id: total-ozone-mapping-spectrometer-20260505-0
file: data/en.wikipedia.org/wiki/Total_Ozone_Mapping_Spectrometer-0.md
category: reference
title: Total Ozone Mapping Spectrometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Total_Ozone_Mapping_Spectrometer
date_saved: 2026-05-05T09:46:22.162336+00:00
instance: kb-cron
parent: total-ozone-mapping-spectrometer-20260505-0
summary:
The Total Ozone Mapping Spectrometer (TOMS) was a NASA satellite instrument, specifically a spectrometer, for measuring the ozone layer. Of the five TOMS instruments which were built, four entered successful orbit. The satellites carrying TOMS instruments were: Nimbus 7; launched October 24, 1978. Operated until 1 August 1994. Carried TOMS instrument number 1. Meteor-3-5; launched 15 August 1991. Operated until December 1994. Was the first and last Soviet satellite to carry a USA made instrument. Carried TOMS instrument number 2. ADEOS I; launched 17 August 1996. Operated until 30 June 1997. Mission was cut short by a spacecraft failure. TOMS-Earth Probe; launched on July 2, 1996. Operated until 2 December 2006. Carried TOMS instrument number 3. QuikTOMS; launched 21 September 2001. Suffered launch failure and did not enter orbit. Nimbus 7 and Meteor-3-5 provided global measurements of total column ozone on a daily basis and together provided a complete data set of daily ozone from November 1978 to December 1994. After an eighteen-month period when the program had no on-orbit capability, TOMS-Earth Probe launched on 2 July 1996, followed by ADEOS I. ADEOS I was launched on August 17, 1996, and the TOMS-instrument onboard provided data until the satellite which


id: tropospheric-emission-spectrometer-20260505-0
file: data/en.wikipedia.org/wiki/Tropospheric_Emission_Spectrometer-0.md
category: reference
title: Tropospheric Emission Spectrometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Tropospheric_Emission_Spectrometer
date_saved: 2026-05-05T09:46:23.334091+00:00
instance: kb-cron
parent: tropospheric-emission-spectrometer-20260505-0
summary:
Tropospheric Emission Spectrometer or TES was a satellite instrument designed to measure the state of the earth's troposphere. == Overview == TES was a high-resolution infrared Fourier Transform spectrometer and provided key data for studying tropospheric chemistry, troposphere-biosphere interaction, and troposphere-stratosphere exchanges. It was built for NASA by the Jet Propulsion Laboratory, California Institute of Technology in Pasadena, California. It was successfully launched into polar orbit by a Delta II 7920-10L rocket aboard NASA's third Earth Observing Systems spacecraft (EOS-Aura) at 10:02 UTC on July 15, 2004. Originally planned as a 5-year mission, it was decommissioned after almost 14 years on January 31, 2018. == References == == External links == NASA JPL's TES page NASA Aura TES page


id: tropospheric-emissions-monitoring-of-pollution-20260505-0
file: data/en.wikipedia.org/wiki/Tropospheric_Emissions:_Monitoring_of_Pollution-0.md
category: reference
title: Tropospheric Emissions: Monitoring of Pollution
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Tropospheric_Emissions:_Monitoring_of_Pollution
date_saved: 2026-05-05T09:46:24.579325+00:00
instance: kb-cron
parent: tropospheric-emissions-monitoring-of-pollution-20260505-0
summary:
Tropospheric Emissions: Monitoring of Pollution (TEMPO) is a space-based spectrometer designed to measure air pollution across greater North America at a high resolution and on an hourly basis. The ultraviolet–visible spectrometer will provide hourly data on ozone, nitrogen dioxide, and formaldehyde in the atmosphere. TEMPO is a hosted payload on a commercial geostationary communication satellite with a constant view of North America. TEMPO's spectrometer measures reflected sunlight from the Earth's atmosphere and separates it into 2,000 component wavelengths. It will scan North America from the Pacific Ocean to the Atlantic Ocean and from the Alberta oil sands to Mexico City. TEMPO will form part of a geostationary constellation of pollution-monitoring assets, along with the planned Sentinel-4 from ESA and Geostationary Environment Monitoring Spectrometer (GEMS) from South Korea's KARI. On 3 February 2020, Intelsat announced that the Intelsat 40e satellite will host TEMPO. Maxar Technologies, the builder of the satellite, is responsible for payload integration. The launch occurred on 7 April 2023. == Earth Venture-Instrument program == TEMPO, which is a collaboration between NASA and the Smithsonian Astrophysical Observatory, is NASA's first Earth Venture-Instrument (EVI) mission. The EVI program is an element within the Earth System Science Pathfinder (ESSP) program office,


id: urey-instrument-20260505-0
file: data/en.wikipedia.org/wiki/Urey_instrument-0.md
category: reference
title: Urey instrument
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Urey_instrument
date_saved: 2026-05-05T09:46:25.784106+00:00
instance: kb-cron
parent: urey-instrument-20260505-0
summary:
The Urey instrument, or Urey: Mars Organic and Oxidant Detector was a developmental spacecraft instrument for detecting organic compounds including amino acids. == Overview == It was funded by NASA and tested in the Atacama Desert in the early 2000s. Urey was selected by NASA for further development in support ExoMars or any future Mars mission that could use Urey along with Mars Organic Molecule Analyzer, or Moma in 2007, funded with 1.5 million USD total (750k each). Urey was a suite of instruments that built on 15 years of research into detecting organic molecules. Urey is a design for in situ biomarker detection, and it was tested in the early 2000s. The device would also study the mysterious oxidants in Mars regolith. Urey was previously included on ExoMars rover, now the Rosalind Franklin rover, in one of its iterations, and would have searched for organic compounds in Martian rocks and soils as evidence for past life and/or prebiotic chemistry. Starting with a hot water extraction, only soluble compounds are left for further analysis. Sublimation, and capillary electrophoresis makes it possible to identify amino acids. The detection would be by laser-induced fluorescence, a highly sensitive technique, capable of parts-per-trillion sensitivity.


id: uvs-juno-20260505-0
file: data/en.wikipedia.org/wiki/UVS_(Juno)-0.md
category: reference
title: UVS (Juno)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/UVS_(Juno)
date_saved: 2026-05-05T09:46:41.188598+00:00
instance: kb-cron
parent: uvs-juno-20260505-0
summary:
UVS, known as the Ultraviolet Spectrograph or Ultraviolet Imaging Spectrometer is the name of an instrument on the Juno orbiter for Jupiter. The instrument is an imaging spectrometer that observes the ultraviolet range of light wavelengths, which is shorter wavelengths than visible light but longer than X-rays. Specifically, it is focused on making remote observations of the aurora, detecting the emissions of gases such as hydrogen in the far-ultraviolet. UVS will observes light from as short a wavelength as 70 nm up to 200 nm, which is in the extreme and far ultraviolet range of light. The source of aurora emissions of Jupiter is one of the goals of the instrument. UVS is one of many instruments on Juno, but it is in particular designed to operate in conjunction with JADE, which observes high-energy particles. With both instruments operating together, both the UV emissions and high-energy particles at the same place and time can be synthesized. This supports the Goal of determining the source of the Jovian magnetic field. There has been a problem understanding the Jovian aurora, ever since Chandra determined X-rays were coming not from, as it was thought Io's orbit but from the polar regions. Every 45


id: venetia-burney-student-dust-counter-20260505-0
file: data/en.wikipedia.org/wiki/Venetia_Burney_Student_Dust_Counter-0.md
category: reference
title: Venetia Burney Student Dust Counter
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Venetia_Burney_Student_Dust_Counter
date_saved: 2026-05-05T09:46:42.373489+00:00
instance: kb-cron
parent: venetia-burney-student-dust-counter-20260505-0
summary:
The Venetia Burney Student Dust Counter (VBSDC) is a scientific instrument aboard the uncrewed New Horizons space probe that is designed to detect dust impacts in outer space. VBSDC is the first planetary science instrument to be built by students. The dust counter was launched in 2006, and named later that year after Venetia Burney, the young girl who originally named Pluto. The detector works when dust strikes films of polarized polyvinylidene fluoride (PVDF), which generates an electrical charge. The space dust is then detected over the course of the New Horizons spacecraft flight out of the Solar System and past Pluto. == Overview == In 2010, VBSDC collected data on dust past 18 AU (1.67 billion miles), which is the distance the Pioneer 10 and Pioneer 11 dust counters stopped working. Five other spacecraft have carried dust detectors beyond the asteroid belt including Pioneer 10, Pioneer 11, Ulysses (heliocentric orbit out to the distance of Jupiter), Galileo (Jupiter Orbiter), and Cassini (Saturn orbiter). The Voyager 1 and Voyager 2 spacecraft did detect dust by using data from the Plasma Wave instrument, but did not have dedicated dust detection instruments. The Pioneer dust detectors stopped working at 18 AU. The


id: venus-emissivity-mapper-20260505-0
file: data/en.wikipedia.org/wiki/Venus_Emissivity_Mapper-0.md
category: reference
title: Venus Emissivity Mapper
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Venus_Emissivity_Mapper
date_saved: 2026-05-05T09:46:43.653791+00:00
instance: kb-cron
parent: venus-emissivity-mapper-20260505-0
summary:
The Venus Emissivity Mapper (VEM) is a spectrometer for mapping the surface composition of Venus through a distinct number of atmospheric spectral windows. It will be one of the two payloads on board the VERITAS mission, and will also be the VenSpec-M channel of the EnVision mission's spectrometer suite. == Overview == While Earth and Venus are similar in many aspects, they evolved very differently and currently have distinct surface and atmospheric environments. Where Earth's surface has liquid water and supports life, Venus experiences a mean surface temperature of over 400 °C, and a carbon dioxide rich atmosphere with a surface pressure of about 92 times that of Earth at sea-level. Little is known about Venus' surface composition. The dense atmosphere and its cloud layers are mostly opaque to visible and infrared radiation, making remote sensing a challenge. As light travels through the atmosphere, it is attenuated by absorption and scattering, and it is blurred by the emissions of the atmosphere itself. Observations of Venus have shown that the surface can be observed through a number of narrow infrared bands. Using this technique Venus Express was able to observe fresh basalt, pointing towards recent volcanic activity on the surface. The


id: venus-emissivity-mapper-20260505-1
file: data/en.wikipedia.org/wiki/Venus_Emissivity_Mapper-1.md
category: reference
title: Venus Emissivity Mapper
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Venus_Emissivity_Mapper
date_saved: 2026-05-05T09:46:43.653791+00:00
instance: kb-cron
parent: venus-emissivity-mapper-20260505-0
summary:
The optics sub-system is a three lens system, provided by LESIA, Observatoire de Paris, France. First, a telescope with an aperture of 8 mm and a focal length of 40.5 mm projects the scene on the filter array. From there, it is then imaged on the focal plane through two more lenses with a combined magnification factor of 0.4. The optics have a total transmittance of 0.88, not taking into account the filters. The focal plane array (VEMFPA) consists of a Xenics XSW-640 InGaAs detector, which has a resolution of 640x512 pixel, a FOV of 30°×45°, a pixel pitch of 20 μm, and a pixel FOV of 0.07°×0.07°. The imaging electronics unit used is LM98640QML-SP from Texas Instruments. InGaAs detectors have been used in deep space successfully over many years, making it a safe choice. This specific unit is currently in use on the ExoMars Trace Gas Orbiter. The filter array is provided by CNES Toulouse Archived 2022-03-14 at the Wayback Machine, France. Narrow-band filters takes care of only transmitting the spectral region of interest. Based on the 4% relative emissivity that is needed to differentiate between the different rock types, the signal-to-noise ratio (SNR) for each band is derived


id: viking-lander-biological-experiments-20260505-0
file: data/en.wikipedia.org/wiki/Viking_lander_biological_experiments-0.md
category: reference
title: Viking lander biological experiments
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Viking_lander_biological_experiments
date_saved: 2026-05-05T09:46:44.854256+00:00
instance: kb-cron
parent: viking-lander-biological-experiments-20260505-0
summary:
In 1976 two identical Viking program landers each carried four types of biological experiments to the surface of Mars. The first successful Mars landers, Viking 1 and Viking 2, then carried out experiments to look for biosignatures of microbial life on Mars. The landers each used a robotic arm to pick up and place soil samples into sealed test containers on the craft. The two landers carried out the same tests at two places on Mars' surface, Viking 1 near the equator and Viking 2 further north. == The experiments == The four experiments below are presented in the order in which they were carried out by the two Viking landers. The biology team leader for the Viking program was Harold P. Klein (NASA Ames). === Gas chromatograph – mass spectrometer === A gas chromatograph – mass spectrometer (GCMS) is a device that separates vapor components chemically via a gas chromatograph and then feeds the result into a mass spectrometer, which measures the molecular weight of each chemical. As a result, it can separate, identify, and quantify a large number of different chemicals. The GCMS (PI: Klaus Biemann, MIT) was used to analyze the components of untreated Martian soil, and


id: viking-lander-biological-experiments-20260505-1
file: data/en.wikipedia.org/wiki/Viking_lander_biological_experiments-1.md
category: reference
title: Viking lander biological experiments
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Viking_lander_biological_experiments
date_saved: 2026-05-05T09:46:44.854256+00:00
instance: kb-cron
parent: viking-lander-biological-experiments-20260505-0
summary:
=== Labeled release === The labeled release (LR) experiment (PI: Gilbert Levin, Biospherics Inc.) gave the most promise for exobiologists. In the LR experiment, a sample of Martian soil was inoculated with a drop of very dilute aqueous nutrient solution. The nutrients (7 molecular compounds that were Miller-Urey products) were tagged with radioactive 14C. The air above the soil was monitored for the evolution of radioactive 14CO2 (or other carbon-based) gas as evidence that microorganisms in the soil had metabolized one or more of the nutrients. Such a result was to be followed with the control part of the experiment as described for the PR below. The result was quite a surprise, considering the negative results of the first two tests, with a steady stream of radioactive gases being given off by the soil immediately following the first injection. The experiment was done by both Viking probes, the first using a sample from the surface exposed to sunlight and the second probe taking the sample from underneath a rock; both initial injections came back positive. Sterilization control tests were subsequently carried out by heating various soil samples. Samples heated for 3 hours at 160 °C gave off no radioactive gas


id: viking-lander-biological-experiments-20260505-2
file: data/en.wikipedia.org/wiki/Viking_lander_biological_experiments-2.md
category: reference
title: Viking lander biological experiments
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Viking_lander_biological_experiments
date_saved: 2026-05-05T09:46:44.854256+00:00
instance: kb-cron
parent: viking-lander-biological-experiments-20260505-0
summary:
Organic compounds seem to be common, for example, on asteroids, meteorites, comets and the icy bodies orbiting the Sun, so detecting no trace of any organic compound on the surface of Mars came as a surprise. The GC-MS was definitely working, because the controls were effective and it was able to detect traces of chlorine, attributed to the cleaning solvents that had been used to sterilize it prior to launch. A reanalysis of the GC-MS data was performed in 2018, suggesting that organic compounds may actually have been detected, corroborating with data from the Curiosity rover. At the time, the total absence of organic material on the surface made the results of the biology experiments moot, since metabolism involving organic compounds were what those experiments were designed to detect. The general scientific community surmises that the Viking's biological tests remain inconclusive, and can be explained by purely chemical processes. Despite the positive result from the Labeled Release experiment, a general assessment is that the results seen in the four experiments are best explained by oxidative chemical reactions with the Martian soil. One of the current conclusions is that the Martian soil, being continuously exposed to UV light from the Sun


id: viking-lander-biological-experiments-20260505-3
file: data/en.wikipedia.org/wiki/Viking_lander_biological_experiments-3.md
category: reference
title: Viking lander biological experiments
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Viking_lander_biological_experiments
date_saved: 2026-05-05T09:46:44.854256+00:00
instance: kb-cron
parent: viking-lander-biological-experiments-20260505-0
summary:
== Controversy == Before the discovery of the oxidizer perchlorate on Mars in 2008, some theories remained opposed to the general scientific conclusion. An investigator suggested that the biological explanation of the lack of detected organics by GC-MS could be that the oxidizing inventory of the H2O2-H2O solvent well exceeded the reducing power of the organic compounds of the organisms. It has also been argued that the Labeled Release (LR) experiment detected so few metabolising organisms in the Martian soil, that it would have been impossible for the gas chromatograph to detect them. This view has been put forward by the designer of the LR experiment, Gilbert Levin, who believes the positive LR results are diagnostic for life on Mars. He and others have conducted ongoing experiments attempting to reproduce the Viking data, either with biological or non-biological materials on Earth. While no experiment has ever precisely duplicated the Mars LR test and control results, experiments with hydrogen peroxide-saturated titanium dioxide have produced similar results. While the majority of astrobiologists still conclude that the Viking biological experiments were inconclusive or negative, Gilbert Levin is not alone in believing otherwise. The current claim for life on Mars is grounded on old


id: waves-juno-20260505-0
file: data/en.wikipedia.org/wiki/Waves_(Juno)-0.md
category: reference
title: Waves (Juno)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Waves_(Juno)
date_saved: 2026-05-05T09:46:46.071009+00:00
instance: kb-cron
parent: waves-juno-20260505-0
summary:
Waves is an experiment on the Juno spacecraft for studying radio and plasma waves. It is part of a collection of various types of instruments and experiments on the spacecraft; Waves is oriented towards understanding fields and particles in the Jupiter's magnetosphere. Waves is on board the uncrewed Juno spacecraft, which was launched in 2011 and arrived at Jupiter in the summer of 2016. The major focus of study for Waves is Jupiter's magnetosphere, which if could be seen from Earth would be about twice the size of a full moon. The magnetosphere has a tear drop shape, and that tail extends away from the Sun by at least 5 AU (Earth-Sun distances). The Waves instrument is designed to help understand the interaction between Jupiter's atmosphere, its magnetic field, its magnetosphere, and to understand Jupiter's auroras. It is designed to detect radio frequencies from 50 Hz up to 40,000,000 Hz (40 MHz), and magnetic fields from 50 Hz to 20,000 Hz (20 kHz). It has two main sensors: a dipole antenna and a magnetic search coil. The dipole antenna has two whip antennas that extend 2.8 meters (110 inches/ 9.1 feet) and are attached to the main body of the


id: wisdom-radar-20260505-0
file: data/en.wikipedia.org/wiki/WISDOM_(radar)-0.md
category: reference
title: WISDOM (radar)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/WISDOM_(radar)
date_saved: 2026-05-05T09:46:47.299152+00:00
instance: kb-cron
parent: wisdom-radar-20260505-0
summary:
WISDOM (Water Ice and Subsurface Deposit Observation on Mars) is a ground-penetrating radar that is part of the science payload on board the European Space Agency's Rosalind Franklin rover, tasked to search for biosignatures and biomarkers on Mars. The rover is planned to be launched not earlier than 2028 and land on Mars in 2029. == Overview == The search for evidence of past or present life on Mars is the principal objective of the ExoMars programme. If such evidence exists, it will most likely be in the subsurface, where organic molecules are shielded from the destructive effects of ionizing radiation and atmospheric oxidants. For this reason, the Rosalind Franklin rover mission has been optimized to investigate the subsurface and sample those locations where conditions for the preservation of evidence of past life are most likely to be found. WISDOM is a step frequency radar that operates in the frequency range from 0.5 to 3 GHz. It will provide high-resolution 3D imaging down to a depth of 3 metres. WISDOM will use UHF radar pulses to provide the three-dimensional geological context of the shallow subsurface underneath the ExoMars rover. It will be used to identify optimal drilling sites and to


id: exolife-finder-20260505-0
file: data/en.wikipedia.org/wiki/ExoLife_Finder-0.md
category: reference
title: ExoLife Finder
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/ExoLife_Finder
date_saved: 2026-05-05T09:46:48.916937+00:00
instance: kb-cron
parent: exolife-finder-20260505-0
summary:
The ExoLife Finder (ELF) telescope is an under-development, hybrid interferometric telescope being designed at the Instituto de Astrofisica de Canarias (IAC) for the direct detection and imaging of exoplanets and potentially water-bearing exoplanets. Developed by a collaboration of scientists and engineers including the PLANETS Foundation, the ELF aims to analyze the surfaces and atmospheres of exoplanets for evidence of life, focusing on nearby star systems within 25 light years of Earth. The telescope's design features non-redundant circular arrays of 5-meter-scale mirrors and tensegrity-based mechanical support with an outer diameter of 35m. It uses multiple layers of advanced atmospheric wavefront sensing and control. It is a scalable optical concept, and could be built within a 10 year timeframe. A 3.5-meter precursor called the Small ELF (SELF) is currently being built in the Canary Islands. The ELF's first targets will include nearby stars cooler than the Sun. ELF incorporates several new technologies in order to study exoplanets that could be 100 million times fainter than the stars they orbit. This combination of technologies results in smoother and lighter optics compared to conventional telescope mirrors and greater control of optical diffraction and wavefront errors created by the atmosphere. According to the team behind


id: telescope-20260505-0
file: data/en.wikipedia.org/wiki/Telescope-0.md
category: reference
title: Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Telescope
date_saved: 2026-05-05T09:46:50.137020+00:00
instance: kb-cron
parent: telescope-20260505-0
summary:
A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally, it was an optical instrument using lenses, curved mirrors, or a combination of both to observe distant objects – an optical telescope. Nowadays, the word "telescope" is defined as a wide range of instruments capable of detecting different regions of the electromagnetic spectrum, and in some cases other types of detectors. The first known practical telescopes were refracting telescopes with glass lenses and were invented in the Netherlands at the beginning of the 17th century. They were used for both terrestrial applications and astronomy. The reflecting telescope, which uses mirrors to collect and focus light, was invented within a few decades of the first refracting telescope. In the 20th century, many new types of telescopes were invented, including radio telescopes in the 1930s and infrared telescopes in the 1960s. == Etymology == The word telescope was coined in 1611 by the Greek mathematician Giovanni Demisiani for one of Galileo Galilei's instruments presented at a banquet at the Accademia dei Lincei. In the Starry Messenger, Galileo had used the Latin term perspicillum. The root of the word is from the Ancient


id: telescope-20260505-1
file: data/en.wikipedia.org/wiki/Telescope-1.md
category: reference
title: Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Telescope
date_saved: 2026-05-05T09:46:50.137020+00:00
instance: kb-cron
parent: telescope-20260505-0
summary:
=== Radio and submillimeter === Radio telescopes are directional radio antennas that typically employ a large dish to collect radio waves. The dishes are sometimes constructed of a conductive wire mesh whose openings are smaller than the wavelength being observed. Unlike an optical telescope, which produces a magnified image of the patch of sky being observed, a traditional radio telescope dish contains a single receiver and records a single time-varying signal characteristic of the observed region; this signal may be sampled at various frequencies. In some newer radio telescope designs, a single dish contains an array of several receivers; this is known as a focal-plane array. By collecting and correlating signals simultaneously received by several dishes, high-resolution images can be computed. Such multi-dish arrays are known as astronomical interferometers and the technique is called aperture synthesis. The 'virtual' apertures of these arrays are similar in size to the distance between the telescopes. As of 2005, the record array size is many times the diameter of the Earth – using space-based very-long-baseline interferometry (VLBI) telescopes such as the Japanese HALCA (Highly Advanced Laboratory for Communications and Astronomy) VSOP (VLBI Space Observatory Program) satellite. Aperture synthesis is now also being applied to


id: 400-years-of-the-telescope-20260505-0
file: data/en.wikipedia.org/wiki/400_Years_of_the_Telescope-0.md
category: reference
title: 400 Years of the Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/400_Years_of_the_Telescope
date_saved: 2026-05-05T09:46:51.340241+00:00
instance: kb-cron
parent: 400-years-of-the-telescope-20260505-0
summary:
400 Years of the Telescope: A Journey of Science, Technology and Thought is a 2009 American documentary film that was created to coincide with the International Year of Astronomy in 2009. Directed by Kris Koenig, it chronicles the history of the telescope from the time of Galileo and features interviews with leading astrophysicists and cosmologists from around the world, who explain concepts ranging from Galileo's first use of the telescope to view the moons of Jupiter, to the latest discoveries in space, including new ideas about life on other planets and dark energy, a mysterious vacuum energy that is accelerating the expansion of the universe. == Cast == === Actors === Han Beekman Mavt Steketee Stefano Lecci Herman Boerman Irma Hartog Hallam Murray Nils Koenig Madison Royal Galileo voices Stefano Lecci Francesca Giannini == Production == The film's development team included Donald Goldsmith, a well-known astronomy writer on the Carl Sagan Cosmos team, and Albert Van Helden, a leading authority on the history of the telescope. It was shot on RED Digital Cinema at the world's leading universities and observatories including the European Southern Observatory, Institute for Astronomy, SETI Institute, Space Telescope Science Institute, Anglo-Australian Observatory, and Harvard University. Among


id: active-optics-20260505-0
file: data/en.wikipedia.org/wiki/Active_optics-0.md
category: reference
title: Active optics
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Active_optics
date_saved: 2026-05-05T09:46:52.527679+00:00
instance: kb-cron
parent: active-optics-20260505-0
summary:
Active optics is a technology used with reflecting telescopes developed in the 1980s, which actively shapes a telescope's mirrors to prevent deformation due to external influences such as wind, temperature, and mechanical stress. Without active optics, the construction of 8 metre class telescopes is not possible, nor would telescopes with segmented mirrors be feasible. This method is used by, among others, the Nordic Optical Telescope, the New Technology Telescope, the Telescopio Nazionale Galileo and the Keck telescopes, as well as all of the largest telescopes built since the mid-1990s. Active optics is not to be confused with adaptive optics, which operates at a shorter timescale and corrects atmospheric distortions. == In astronomy == Most modern telescopes are reflectors, with the primary element being a very large mirror. Historically, primary mirrors were quite thick in order to maintain the correct surface figure in spite of forces tending to deform it, like wind and the mirror's own weight. This limited their maximum diameter to 5 or 6 metres (200 or 230 inches), such as Palomar Observatory's Hale Telescope. A new generation of telescopes built since the 1980s uses thin, lighter weight mirrors instead. They are too thin to maintain themselves rigidly in


id: adaptive-optics-20260505-0
file: data/en.wikipedia.org/wiki/Adaptive_optics-0.md
category: reference
title: Adaptive optics
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Adaptive_optics
date_saved: 2026-05-05T09:46:53.774429+00:00
instance: kb-cron
parent: adaptive-optics-20260505-0
summary:
Adaptive optics (AO) is a technique of precisely deforming a mirror in order to compensate for light distortion. It is used in astronomical telescopes and laser communication systems to remove the effects of atmospheric distortion, in microscopy, optical fabrication and in retinal imaging systems (ophthalmoscopy) to reduce optical aberrations. Adaptive optics works by measuring the distortions in a wavefront and compensating for them with a device that corrects those errors such as a deformable mirror or a liquid crystal array. Adaptive optics should not be confused with active optics, which work on a longer timescale to correct the primary mirror geometry. Other methods can achieve resolving power exceeding the limit imposed by atmospheric distortion, such as speckle imaging, aperture synthesis, and lucky imaging, or by moving outside the atmosphere with space telescopes, such as the Hubble Space Telescope. == History == Adaptive optics was first envisioned by Horace W. Babcock in 1953, and was also considered in science fiction, as in Poul Anderson's novel Tau Zero (1970), but it did not come into common usage until advances in computer technology during the 1990s made the technique practical. Some of the initial development work on adaptive optics was done by the


id: adaptive-optics-20260505-1
file: data/en.wikipedia.org/wiki/Adaptive_optics-1.md
category: reference
title: Adaptive optics
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Adaptive_optics
date_saved: 2026-05-05T09:46:53.774429+00:00
instance: kb-cron
parent: adaptive-optics-20260505-0
summary:
An alternative is the use of a laser beam to generate a reference light source (a laser guide star, LGS) in the atmosphere. There are two kinds of LGSs: Rayleigh guide stars and sodium guide stars. Rayleigh guide stars work by propagating a laser, usually at near ultraviolet wavelengths, and detecting the backscatter from air at altitudes between 15 and 25 km (49,000 and 82,000 ft). Sodium guide stars use laser light at 589 nm to resonantly excite sodium atoms higher in the mesosphere and thermosphere, which then appear to "glow". The LGS can then be used as a wavefront reference in the same way as a natural guide star – except that (much fainter) natural reference stars are still required for image position (tip/tilt) information. The lasers are often pulsed, with measurement of the atmosphere being limited to a window occurring a few microseconds after the pulse has been launched. This allows the system to ignore most scattered light at ground level; only light which has travelled for several microseconds high up into the atmosphere and back is actually detected.} == In retinal imaging == Adaptive optics has applications in ophthalmology. Ocular aberrations are distortions in the wavefront passing


id: adaptive-optics-20260505-2
file: data/en.wikipedia.org/wiki/Adaptive_optics-2.md
category: reference
title: Adaptive optics
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Adaptive_optics
date_saved: 2026-05-05T09:46:53.774429+00:00
instance: kb-cron
parent: adaptive-optics-20260505-0
summary:
Besides its use for improving nighttime astronomical imaging and retinal imaging, adaptive optics technology has also been used in other settings. Adaptive optics is used for solar astronomy at observatories such as the Swedish 1-m Solar Telescope, Dunn Solar Telescope, and Big Bear Solar Observatory. It is also expected to play a military role by allowing ground-based and airborne laser weapons to reach and destroy targets at a distance including satellites in orbit. The Missile Defense Agency Airborne Laser program is the principal example of this. Adaptive optics has been used to enhance the performance of classical and quantum free-space optical communication systems, and to control the spatial output of optical fibers. Medical applications include imaging of the retina, where it has been combined with optical coherence tomography. Also the development of Adaptive Optics Scanning Laser Ophthalmoscope (AOSLO) has enabled correcting for the aberrations of the wavefront that is reflected from the human retina and to take diffraction limited images of the human rods and cones. Adaptive and active optics are also being developed for use in glasses to achieve better than 20/20 vision, initially for military applications. After propagation of a wavefront, parts of it may overlap leading to


id: altazimuth-mount-20260505-0
file: data/en.wikipedia.org/wiki/Altazimuth_mount-0.md
category: reference
title: Altazimuth mount
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Altazimuth_mount
date_saved: 2026-05-05T09:46:54.951664+00:00
instance: kb-cron
parent: altazimuth-mount-20260505-0
summary:
An altazimuth mount or alt-azimuth mount is a simple two-axis mount for supporting and rotating an instrument about two perpendicular axes – one vertical and the other horizontal. Rotation about the vertical axis varies the azimuth (compass bearing) of the pointing direction of the instrument. Rotation about the horizontal axis varies the altitude angle (angle of elevation) of the pointing direction. These mounts are used, for example, with telescopes, cameras, radio antennas, heliostat mirrors, solar panels, and guns and similar weapons. Several names are given to this kind of mount, including altitude-azimuth, azimuth-elevation and various abbreviations thereof. A gun turret is essentially an alt-azimuth mount for a gun, and a standard camera tripod is an alt-azimuth mount as well. == Astronomical telescope altazimuth mounts == When used as an astronomical telescope mount, the biggest advantage of an alt-azimuth mount is the simplicity of its mechanical design. The primary disadvantage is its inability to follow astronomical objects in the night sky as the Earth spins on its axis. On the other hand, an equatorial mount only needs to be rotated about a single axis, at a constant rate, to follow the rotation of the night sky (diurnal motion). Altazimuth mounts need


id: antique-telescope-society-20260505-0
file: data/en.wikipedia.org/wiki/Antique_Telescope_Society-0.md
category: reference
title: Antique Telescope Society
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Antique_Telescope_Society
date_saved: 2026-05-05T09:46:56.137084+00:00
instance: kb-cron
parent: antique-telescope-society-20260505-0
summary:
The Antique Telescope Society (ATS) is a society for people interested in antique telescopes, binoculars, instruments, books, atlases, etc. It was established in 1992 and presently based in Virginia, the USA. The society has an annual meeting. It also publishes the Journal of the Antique Telescope Society and has an active email list. The American astronomer Michael D. Reynolds was the President of the Antique Telescope Society. == References == == External links == Antique Telescope Society website Antique Telescope Society on Facebook


id: aragoscope-20260505-0
file: data/en.wikipedia.org/wiki/Aragoscope-0.md
category: reference
title: Aragoscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Aragoscope
date_saved: 2026-05-05T09:46:57.331564+00:00
instance: kb-cron
parent: aragoscope-20260505-0
summary:
An Aragoscope is a telescope design based on diffraction around the edge of an occluding disc, named after French scientist François Arago. == Concept == The light diffracted around the edge of a perfectly circular occluder interferes constructively at the central axis, producing a bright spot known as the Arago spot. The resolution at that point would be equal to the resolution of a conventional lens with the same size as the occluder, although the light would be much less intense. On this basis it would be possible to create a telescope by placing a suitable disc in space accompanied by a separate telescope some distance away along its axis. This concept has been explored by NASA and received Phase One funding in June 2014 by the NASA Innovative Advanced Concepts (NIAC) program. It is important to note that this is a very different approach from that taken by another NASA project, the New Worlds Mission, which aims to use an occluder with "petals", otherwise known as a starshade, specifically designed to avoid diffraction onto the central axis. == See also == Arago telescope, a 38 cm (15 inch) refractor at Paris Observatory's east tower Zone plate == References ==


id: astrograph-20260505-0
file: data/en.wikipedia.org/wiki/Astrograph-0.md
category: reference
title: Astrograph
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astrograph
date_saved: 2026-05-05T09:46:58.538503+00:00
instance: kb-cron
parent: astrograph-20260505-0
summary:
An astrograph (or astrographic camera) is a telescope designed for the sole purpose of astrophotography. Astrographs are mostly used in wide-field astronomical surveys of the sky and for detection of objects such as asteroids, meteors, and comets. Improvements in photography in the middle 19th century led to designs dedicated to astrophotography, and they were also popular in the 20th century. As in other photography, chemicals were used that respond to light, recorded on a glass photographic plate or sometimes on photographic film. Many observatories of this period used an astrograph, beside instruments like the transit telescope, great refractors, and chronometers, or instruments for observing the Sun. Astrographs were often used to make surveys of the night sky, and one of the famous projects was Carte du Ciel. Discoveries using an astrograph include then-planet Pluto. Rather than looking through the telescope, it was discovered by using a blink comparator with images taken by an astrograph. By the late 20th century, electronic detectors became more common with the data being stored electronically. == Design == Most research telescopes in this class are refractors, although there are many (usually larger) reflecting designs such as the Ritchey-Chrétien and catadioptrics such as the Schmidt camera.


id: astroscan-20260505-0
file: data/en.wikipedia.org/wiki/Astroscan-0.md
category: reference
title: Astroscan
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astroscan
date_saved: 2026-05-05T09:46:59.692385+00:00
instance: kb-cron
parent: astroscan-20260505-0
summary:
The Astroscan was a wide-field 4+1⁄8 in (10 cm) clear-inch diameter reflecting telescope, originally produced by the Edmund Scientific Corporation, that was for sale from 1976 to 2013. == Design == The Astroscan had a Newtonian reflector layout with a 4+1⁄8 in (10 cm) clear-inch diameter f/4.2 aluminized and overcoated borosilicate glass parabolic primary mirror with a focal length of 17+1⁄2 inches (44 cm). The telescope's secondary mirror was mounted on a flat optical window at the front of the tube. Edmund designer Norman Sperling and optical engineer Mike Simmons came up with the basic design and Peter Bressler Design Associates did the detailed work on this simple introductory telescope. Rather than using a more traditional equatorial or altazimuth mount the Astroscan features a spherical housing around the primary reflector which sat in a cast aluminum cradle. The design was durable and allowed for simple operation by novice amateur astronomers; it won an Industrial Design Award in 1976. The telescope body was made from high impact acrylonitrile butadiene styrene (ABS) plastic and was equipped with a carrying strap to aid portability. Because it was targeted at the novice market the telescope had its limitations: The general design was for low


id: atmosphere-and-telescope-simulator-20260505-0
file: data/en.wikipedia.org/wiki/Atmosphere_and_Telescope_Simulator-0.md
category: reference
title: Atmosphere and Telescope Simulator
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Atmosphere_and_Telescope_Simulator
date_saved: 2026-05-05T09:47:00.864770+00:00
instance: kb-cron
parent: atmosphere-and-telescope-simulator-20260505-0
summary:
Atmosphere and Telescope Simulators for astronomy education, are used because time in science-worthy class telescopes are generally expensive and difficult to obtain. Telescope facilities are often uncomfortable for operators working for long periods of time. In addition, Atmosphere and Telescope Simulators can be used to test new adaptive optics systems before using them on real telescopes. Researchers have expressed the need for a laboratory tool which could provide better and cheaper accessibility than a real telescope, and better characterization than computer simulations. A LED based illumination system in which five Galilean collimation systems have been used is reported on. It is part of a turbulence simulator for the evaluation of on ground telescopes instrumentation developed by INTA (optics) and LIDAX (opto-mechanics) for the IAC called IACATS. The IACATS instrument simulates a scene consisting of a set of different binary stars simulating the required angular separation between them, and their spectral characteristics. As a result, a visible and infrared multi-spectral illumination system has been integrated as a part of the turbulence simulator. A wave front sensor enables to evaluate the deformation that the phase plates, or the simulated turbulence, produce in the wave front coming from the illumination system and star


id: automated-patrol-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Automated_Patrol_Telescope-0.md
category: reference
title: Automated Patrol Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Automated_Patrol_Telescope
date_saved: 2026-05-05T09:47:02.037691+00:00
instance: kb-cron
parent: automated-patrol-telescope-20260505-0
summary:
The Automated Patrol Telescope (APT) was a wide-field CCD imaging telescope, operated by the University of New South Wales at Siding Spring Observatory, Australia. The telescope activated in June 1989. This was one of four (4) ROTSE telescopes around the World to detect Gamma ray bursts, with telescopes positioned in Australia, Namibia, Turkey, and Texas. The telescope was designed for robotic use, with 45 cm aperture. The telescope was converted for computer controlled operation and CCD imaging from an older retired Baker-nunn camera. This is a type of modified Schmidt canera. The telescope has a field of view of 5 degrees by 5 degrees. == See also == List of telescopes of Australia Lists of telescopes == References == == Further reading == Preliminary results from the Automated Patrol Telescope CCD camera (1990) == External links == Automated Patrol Telescope (APT) on the internet


id: automated-planet-finder-20260505-0
file: data/en.wikipedia.org/wiki/Automated_Planet_Finder-0.md
category: reference
title: Automated Planet Finder
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Automated_Planet_Finder
date_saved: 2026-05-05T09:47:03.209030+00:00
instance: kb-cron
parent: automated-planet-finder-20260505-0
summary:
The Automated Planet Finder (APF) Telescope a.k.a. Rocky Planet Finder, is a fully robotic 2.4-meter optical telescope at Lick Observatory, situated on the summit of Mount Hamilton, east of San Jose, California, USA. It is designed to search for extrasolar planets in the range of five to twenty times the mass of the Earth. The instrument will examine about 10 stars per night. Over the span of a decade, the telescope is expected to study 1,000 nearby stars for planets. Its estimated cost was $10 million. The total cost-to-completion of the APF project was $12.37 million. First light was originally scheduled for 2006, but delays in the construction of the major components of the telescope pushed this back to August 2013. It was commissioned in August 2013. The telescope uses high-precision radial velocity measurements to measure the gravitational reflex motion of nearby stars caused by the orbiting of planets. The design goal is to detect stellar motions as small as one meter per second, comparable to a slow walking speed. The main targets will be stars within about 100 light years of the Earth. Early tests show that the performance of the Ken and Gloria Levy Doppler Spectrometer is meeting


id: bahtinov-mask-20260505-0
file: data/en.wikipedia.org/wiki/Bahtinov_mask-0.md
category: reference
title: Bahtinov mask
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bahtinov_mask
date_saved: 2026-05-05T09:47:04.393446+00:00
instance: kb-cron
parent: bahtinov-mask-20260505-0
summary:
The Bahtinov mask is a device used to focus small astronomical telescopes accurately. Although masks have long been used as focusing aids, the distinctive pattern was invented by Russian amateur astrophotographer Pavel Bahtinov (Russian: Павел Бахтинов) in 2005. Precise focusing of telescopes and astrographs is critical to performing astrophotography. The telescope is pointed at a bright star, and a mask is placed in front of the telescope's objective (or in front of the aperture). The mask consists of three separate grids, positioned in such a way that the grids produce three angled diffraction spikes at the focal plane of the instrument for each bright image element. As the instrument's focus is changed, the central spike appears to move from one side of the star to the other. In reality, all three spikes move, but the central spike moves in the opposite direction to the two spikes forming the "X". Optimal focus is achieved when the middle spike is centered between the other two spikes. Small deviations from optimal focus are easily visible. For astrophotography, a digital image can be analyzed by software to locate the alignment of the spikes to sub-pixel resolution. The direction of this displacement indicates the direction


id: birmingham-solar-oscillations-network-20260505-0
file: data/en.wikipedia.org/wiki/Birmingham_Solar_Oscillations_Network-0.md
category: reference
title: Birmingham Solar Oscillations Network
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Birmingham_Solar_Oscillations_Network
date_saved: 2026-05-05T09:47:05.609315+00:00
instance: kb-cron
parent: birmingham-solar-oscillations-network-20260505-0
summary:
The Birmingham Solar Oscillations Network (BiSON) consists of a network of six remote solar observatories monitoring low-degree solar oscillation modes. It is operated by the High Resolution Optical Spectroscopy group of the School of Physics and Astronomy at the University of Birmingham, UK, in collaboration with Sheffield Hallam University, UK. They are funded by the Science and Technology Facilities Council (STFC). The BiSON has been collecting data continuously on solar oscillations since 1976, making it the longest running helioseismology network with data covering three solar cycles. == Team == === Academic staff === Professor Yvonne Elsworth (Head of project) Professor Bill Chaplin === Research staff === Anne-Marie Broomhall — Helioseismology Andrea Miglio Steven Hale === Technical staff === Mr Ian Barnes — Electronics Mr Barry Jackson — Mechanics == Remote observatories == BiSON operates automated resonant scattering spectrometers in astronomical domes or mirror fed systems. The network was established in 1976 with two permanent stations; the addition of several more sites culminated with the addition of a sixth in 1992. The current sites are: Mount Wilson Observatory, California, USA Las Campanas Observatory, Region IV, Chile Observatorio del Teide, Tenerife, Canary Islands, Spain South African Astronomical Observatory, Sutherland, South Africa OTC


id: carey-mask-20260505-0
file: data/en.wikipedia.org/wiki/Carey_mask-0.md
category: reference
title: Carey mask
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Carey_mask
date_saved: 2026-05-05T09:47:06.765661+00:00
instance: kb-cron
parent: carey-mask-20260505-0
summary:
A Carey mask (named after the inventor, George F. Carey) is a focusing aid for astronomical telescopes. The mask is in the form of a thin card or sheet that is placed over the front aperture of the telescope. There are four series of slits in the mask which form a diffraction pattern in the image plane. In this example the two sets of slits on the left are angled at 12 degrees to each other. Those on the right are angled at 10 degrees to each other. Different telescope and imaging combinations may require slightly different angles. The diffraction pattern caused by the left hand slits will be in the form of an 'X'. The right hand slits will also form an 'X' shape, but the lines forming the 'X' will cross at a narrower angle. When perfect focus is achieved the two 'X's will be superimposed and be perfectly symmetrical. Any slight error in focus will cause the 'X's to be offset, and this is very noticeable to the naked eye. In the example images below, focus error is obvious in the first two images. The third image is very close to perfect focus as shown by the


id: chabot-space-and-science-center-20260505-0
file: data/en.wikipedia.org/wiki/Chabot_Space_and_Science_Center-0.md
category: reference
title: Chabot Space and Science Center
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chabot_Space_and_Science_Center
date_saved: 2026-05-05T09:47:07.984471+00:00
instance: kb-cron
parent: chabot-space-and-science-center-20260505-0
summary:
Chabot Space and Science Center (), located in Oakland, California, is a center for learning in Earth and space science, which features interactive exhibits, planetariums, a large screen theater, hands-on activities, and three powerful telescopes. The center is the continuation and expansion of a public observatory that has served San Francisco Bay Area schools and citizens with astronomy and science education programs since 1883. It is named after the father of hydraulic mining and benefactor of the original Oakland Observatory, Anthony Chabot. Since 2000, the center has been located on the western border of Redwoods Regional Park and has partnered with the National Aeronautics and Space Administration, hosting the NASA Ames Visitor Center. == History == The institution began in 1883 as the Oakland Observatory, through a gift from Anthony Chabot to the City of Oakland. The original Oakland Observatory was located near downtown Oakland and provided public telescope viewing for the community. For decades, it also served as the official timekeeping station for the entire Bay Area, measuring time with its transit telescope. The observatory moved to its Mountain Boulevard location near the current State Route 13 (37°47′13″N 122°10′42″W - telescope domes visible in satellite view) in 1915 due


id: comet-seeker-20260505-0
file: data/en.wikipedia.org/wiki/Comet_seeker-0.md
category: reference
title: Comet seeker
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Comet_seeker
date_saved: 2026-05-05T09:47:09.154621+00:00
instance: kb-cron
parent: comet-seeker-20260505-0
summary:
A comet seeker is a type of small telescope adapted especially to searching for comets: commonly of short focal length and large aperture, in order to secure the greatest brilliancy of light. This style of telescope was used to discover the asteroid 9 Metis in 1848. == Design == A comet seeker telescope is a type of optical device that is known for having a short focal length but a wide field of view. == Examples == A comet seeker with about 3.9 inch aperture was installed at the United States Naval Observatory in 1843, and later transferred to the Smithsonian Museum in 1866. It had an aperture of 4 inches (10.2 cm) and was made by Utzschneider & Fraunhofer in Munich. This was operated as part of suite of several other instruments including a larger refractor on an equatorial mounting, a meridian transit, mural circle, etc. Markree Observatory added a 3-inch aperture Comet Seeker on an equatorial mount by Ertel. It was ordered in 1842, and in place until 1874. The Markree Comet Seeker was used to discover 9 Metis in April 1848. It was discovered by Edward Cooper's assistant Andrew Graham, who worked at that observatory until 1860.


id: compton-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Compton_telescope-0.md
category: reference
title: Compton telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Compton_telescope
date_saved: 2026-05-05T09:47:10.283052+00:00
instance: kb-cron
parent: compton-telescope-20260505-0
summary:
A Compton telescope (also known as Compton camera or Compton imager) is a gamma-ray detector which utilizes Compton scattering to determine the origin of the observed gamma rays. Compton cameras are usually applied to detect gamma rays in the energy range where Compton scattering is the dominating interaction process, from a few hundred keV to several MeV. They are applied in fields such as astrophysics, nuclear medicine, and nuclear threat detection. == Principle of operation == The Compton telescope consists of two layers of Compton scattering detectors spaced apart (1.5 m in the case of COMPTEL). A Compton scattering event results in an electron and a photon. Each layer detects the position of a event and the energy of an electron resulting from the Compton event. In addition, the time between events in the upper and lower layers is measured. When the time between two events matches the time it takes for the photon to travel from the upper to lower level, the events are accepted for a image. The direction of the original gamma ray is unknown but the angle of the second photon and the energies of the two electrons allow the angle between the first and second


id: cophasing-20260505-0
file: data/en.wikipedia.org/wiki/Cophasing-0.md
category: reference
title: Cophasing
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cophasing
date_saved: 2026-05-05T09:47:11.478276+00:00
instance: kb-cron
parent: cophasing-20260505-0
summary:
In astronomy, the term cophasing or phasing describes the process of controlling the individual segments in a segmented mirror or a telescope so that the segments form a larger composite mirroring surface. Cophasing implies precise, active control of three degrees of freedom of each individual segment mirror: translation along the optical axis (piston) and rotation about two axes perpendicular to the optical axis (tip-tilt). Each segment of the segmented telescope is a solid body having 6 degrees of freedom exposed to the gravitation force, wind blowing, and other mechanical forces. If the position of each segment is not controlled the resolution of the whole telescope will be the same as if telescope had the diameter equal to the size of one segment. To achieve a resolution commensurable with that of a monolithic telescope of the same diameter the segmented surface must be controlled with a precision better than λ / 40 {\displaystyle \lambda /40} surface rms. Projects for future extremely large telescopes (ELTs) generally depend on the use of a segmented primary mirror. While the basic technologies required for segmented telescopes have been demonstrated for the 10m Keck telescope or GTC telescope, ELTs of diameters from 50 to 100 m


id: copyscope-20260505-0
file: data/en.wikipedia.org/wiki/Copyscope-0.md
category: reference
title: Copyscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Copyscope
date_saved: 2026-05-05T09:47:12.646818+00:00
instance: kb-cron
parent: copyscope-20260505-0
summary:
A copyscope is type of refracting telescope that can be made by hand rather than bought in which the objective lens comes from an old photocopy machine, hence the origin of the name. The lenses usually come from defective or old photocopiers, allowing for the objective to be obtained for free or at a low cost. They are usually modest diameter lenses, ranging from 50mm to 60mm, of short focal length, good for use in a portable, wide-field telescope, but unsuitable for higher magnifications. Given the use of good components, however, a copyscope can become a rich-field instrument capable of reaching many extended objects and even star fields. == History == The way in which copyscopes are constructed was first shown and explained in the May 1986 issue of Astronomy Magazine by Ken Bird. Surplus photocopier lenses from 200 to 300 mm focal length along with PVC pipe components for the tube and lens holder were used to build the copyscope described in the magazine. == Construction == Copyscopes usually use an objective lens sourced from a photocopier. Usually 50mm to 60mm in diameter, these lenses operate at low f/numbers (f-ratio of around f4 to f6) but cover a large


id: coud-spectrograph-20260505-0
file: data/en.wikipedia.org/wiki/Coudé_Spectrograph-0.md
category: reference
title: Coudé Spectrograph
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coudé_Spectrograph
date_saved: 2026-05-05T09:47:14.150442+00:00
instance: kb-cron
parent: coud-spectrograph-20260505-0
summary:
The Coudé Spectrograph was an instrument attached to the coudé focus of the ESO 1.52-metre telescope (coudé is the French word for elbow). Three cameras equipped with photographic plates as detectors were available. It has two cameras working at f/6 and f/14. Dispersions from 1A/mm to 18a/mm are available with a selection of three gratings, each with ruled areas of 20 x 30 cm. The Coudé Spectrograph was installed at the coudé focus of the ESO 1.52-metre telescope at the La Silla Observatory in May 1969. It was decommissioned from the ESO 1.52-metre telescope in mid 1980s. == References == == External links == Diagram of a Coudé spectrograph.


id: craig-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Craig_telescope-0.md
category: reference
title: Craig telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Craig_telescope
date_saved: 2026-05-05T09:47:15.322173+00:00
instance: kb-cron
parent: craig-telescope-20260505-0
summary:
The Craig telescope was a large telescope built in the 1850s, and while much larger than previous refracting telescopes, it had some problems that hampered its use. Its unique design and potential caused a great deal of excitement in its day. The telescope was ready in August 1852 and was visited by William Parsons, 3rd Earl of Rosse, famous for the Leviathan of Parsonstown, a reflecting telescope and the largest telescope of this age with a six-foot mirror. == Telescope == It was the largest refracting telescope (a telescope with a lens) in the world from 1852 to 1857, erected in south London, England. It was a great refractor, a large refracting telescope with an achromatic doublet with an aperture of 61 cm (2 feet or 24 inches) and was completed in 1852 on Wandsworth Common and dismantled around 1857 (although the brick tower probably survived until 1870). It had a focal length of 76–83 feet. It was named after the Reverend John Craig, who spent a small fortune on it, producing a uniquely designed telescope with nearly double the aperture of the next largest refracting telescopes, making it the largest refracting telescope in the World for the better part


id: dark-energy-spectroscopic-instrument-20260505-0
file: data/en.wikipedia.org/wiki/Dark_Energy_Spectroscopic_Instrument-0.md
category: reference
title: Dark Energy Spectroscopic Instrument
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dark_Energy_Spectroscopic_Instrument
date_saved: 2026-05-05T09:47:16.561008+00:00
instance: kb-cron
parent: dark-energy-spectroscopic-instrument-20260505-0
summary:
The Dark Energy Spectroscopic Instrument (DESI) is a scientific research instrument for conducting spectrographic astronomical surveys of distant galaxies. Its main components are a focal plane containing 5,000 fiber-positioning robots, and a bank of spectrographs which are fed by the fibers. The instrument enables an experiment to probe the expansion history of the universe and the mysterious physics of dark energy. The main DESI survey started in May 2021. DESI sits at an elevation of 6,880 feet (2,100 m), where it has been retrofitted onto the Mayall Telescope on top of Kitt Peak in the Sonoran Desert, which is located 55 miles (89 km) from Tucson, Arizona, United States. The instrument is operated by the Lawrence Berkeley National Laboratory under funding from the U.S. Department of Energy's Office of Science. Construction of the instrument was principally funded by the U.S. Department of Energy's Office of Science, and by other numerous sources including the U.S. National Science Foundation, the British Science and Technology Facilities Council, France's Alternative Energies and Atomic Energy Commission, Mexico's National Council of Science and Technology, Spain's Ministry of Science and Innovation, by the Gordon and Betty Moore Foundation, by the Heising-Simons Foundation, and by collaborating institutions worldwide.


id: dark-energy-spectroscopic-instrument-20260505-1
file: data/en.wikipedia.org/wiki/Dark_Energy_Spectroscopic_Instrument-1.md
category: reference
title: Dark Energy Spectroscopic Instrument
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dark_Energy_Spectroscopic_Instrument
date_saved: 2026-05-05T09:47:16.561008+00:00
instance: kb-cron
parent: dark-energy-spectroscopic-instrument-20260505-0
summary:
== Development == The DESI instrument implements a new highly multiplexed optical spectrograph on the Mayall Telescope. The new optical corrector design creates a very large, 8.0 square degree field of view on the sky, which combined with the new focal plane instrumentation weighs approximately 10 tonnes. The focal plane accommodates 5,000 small robotic fiber positioners on a 10.4 millimeter pitch. The entire focal plane can be reconfigured for the next exposure in less than two minutes while the telescope slews to the next field. The DESI instrument is capable of taking 5,000 simultaneous spectra over a wavelength range from 360 nm to 980 nm. The DESI project scope included construction, installation, and commissioning of the new wide-field corrector and corrector support structure for the telescope, the focal plane assembly with 5,000 robotic fiber positioners and ten guide/focus/alignment sensors, a 40-meter optical fiber cabling system that brings light from the focal plane to the spectrographs, ten 3-arm spectrographs, an instrument control system, and a data analysis pipeline. The instrument fabrication was managed by the Lawrence Berkeley National Laboratory and oversees operation of the experiment including a 600-person international scientific collaboration. Cost of construction was $56M from the US Department of


id: dark-energy-spectroscopic-instrument-20260505-2
file: data/en.wikipedia.org/wiki/Dark_Energy_Spectroscopic_Instrument-2.md
category: reference
title: Dark Energy Spectroscopic Instrument
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dark_Energy_Spectroscopic_Instrument
date_saved: 2026-05-05T09:47:16.561008+00:00
instance: kb-cron
parent: dark-energy-spectroscopic-instrument-20260505-0
summary:
=== Early data release === On 13 June 2023 the DESI Early Data Release (EDR) was announced. The EDR contains spectra of nearly two million galaxies, quasars and stars. One early result of the EDR was announced in February 2023 and described a mass migration of stars into the Andromeda Galaxy. The EDR also revealed very distant quasars and very metal-poor stars. In 2025, a team led by Ragadeepika Pucha of the University of Arizona and the University of Utah reported in The Astrophysical Journal the discovery of the largest number of dwarf galaxies including 2,800 black holes (300 intermediate-mass black holes and 2,500 active black holes) from the EDR. ==== Possibly evolving dark energy levels ==== From the level of detail able to be observed, the largest 3-D map of the universe at this point has been created (2024). From this precise data, DESI Director Michael Levi stated:We’re also seeing some potentially interesting differences that could indicate that dark energy is evolving over time. Those may or may not go away with more data, so we’re excited to start analyzing our three-year dataset soon. === Data Release 1 (DR1) === Data Release 1 (DR1), published on 19 March 2025,


id: diffraction-limited-system-20260505-0
file: data/en.wikipedia.org/wiki/Diffraction-limited_system-0.md
category: reference
title: Diffraction-limited system
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Diffraction-limited_system
date_saved: 2026-05-05T09:47:17.785058+00:00
instance: kb-cron
parent: diffraction-limited-system-20260505-0
summary:
In optics, any optical instrument or system – a microscope, telescope, or camera – has a principal limit to its resolution due to the physics of diffraction. An optical instrument is said to be diffraction-limited if it has reached this limit of resolution performance. Other factors may affect an optical system's performance, such as lens imperfections or aberrations, but these are caused by errors in the manufacture or calculation of a lens, whereas the diffraction limit is the maximum resolution possible for a theoretically perfect, or ideal, optical system. The diffraction-limited angular resolution, in radians, of an instrument is proportional to the wavelength of the light being observed, and inversely proportional to the diameter of its objective's entrance aperture. For telescopes with circular apertures, the size of the smallest feature in an image that is diffraction limited is the size of the Airy disk. As one decreases the size of the aperture of a telescopic lens, diffraction proportionately increases. At small apertures, such as f/22, most modern lenses are limited only by diffraction and not by aberrations or other imperfections in the construction. For microscopic instruments, the diffraction-limited spatial resolution is proportional to the light wavelength, and to the numerical


id: diffraction-limited-system-20260505-1
file: data/en.wikipedia.org/wiki/Diffraction-limited_system-1.md
category: reference
title: Diffraction-limited system
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Diffraction-limited_system
date_saved: 2026-05-05T09:47:17.785058+00:00
instance: kb-cron
parent: diffraction-limited-system-20260505-0
summary:
In the case where the spread of the IRF is small with respect to the spread of the diffraction PSF, in which case the system may be said to be essentially diffraction limited (so long as the lens itself is diffraction limited). In the case where the spread of the diffraction PSF is small with respect to the IRF, in which case the system is instrument limited. In the case where the spread of the PSF and IRF are similar, in which case both impact the available resolution of the system. The spread of the diffraction-limited PSF is approximated by the diameter of the first null of the Airy disk, d / 2 = 1.22 λ N , {\displaystyle d/2=1.22\lambda N,\,} where λ {\displaystyle \lambda } is the wavelength of the light and N {\displaystyle N} is the f-number of the imaging optics, i.e., 2 N A → ( 2.44 N ) − 1 {\displaystyle 2\mathrm {NA} \rightarrow (2.44N)^{-1}} in the Abbe diffraction limit formula. For instance, for an f/8 lens ( N = 8 {\displaystyle N=8} and N A ≈ 2.5 % {\displaystyle \mathrm {NA} \approx 2.5\%} ) and for green light ( λ g = {\displaystyle \lambda _{g}=}


id: diffraction-limited-system-20260505-2
file: data/en.wikipedia.org/wiki/Diffraction-limited_system-2.md
category: reference
title: Diffraction-limited system
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Diffraction-limited_system
date_saved: 2026-05-05T09:47:17.785058+00:00
instance: kb-cron
parent: diffraction-limited-system-20260505-0
summary:
=== Near-field techniques === The diffraction limit is only valid in the far field as it assumes that no evanescent fields reach the detector. Various near-field techniques that operate less than ≈1 wavelength of light away from the image plane can obtain substantially higher resolution. These techniques exploit the fact that the evanescent field contains information beyond the diffraction limit which can be used to construct very high resolution images, in principle beating the diffraction limit by a factor proportional to how well a specific imaging system can detect the near-field signal. For scattered light imaging, instruments such as near-field scanning optical microscopes and nano-FTIR, which are built atop atomic force microscope systems, can be used to achieve up to 10-50 nm resolution. The data recorded by such instruments often requires substantial processing, essentially solving an optical inverse problem for each image. Metamaterial-based superlenses can image with a resolution better than the diffraction limit by locating the objective lens extremely close (typically hundreds of nanometers) to the object. In fluorescence microscopy the excitation and emission are typically on different wavelengths. In total internal reflection fluorescence microscopy a thin portion of the sample located immediately on the cover glass is excited


id: dioptrics-20260505-0
file: data/en.wikipedia.org/wiki/Dioptrics-0.md
category: reference
title: Dioptrics
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dioptrics
date_saved: 2026-05-05T09:47:18.930263+00:00
instance: kb-cron
parent: dioptrics-20260505-0
summary:
Dioptrics is the branch of optics dealing with refraction, especially by lenses. In contrast, the branch dealing with mirrors is known as catoptrics. Telescopes that create their image with an objective that is a convex lens (refractors) are said to be "dioptric" telescopes. An early study of dioptrics was conducted by Ptolemy in relationship to the human eye as well as refraction in media such as water. The understanding of the principles of dioptrics was further expanded by Alhazen, considered the father of modern optics. == See also == Diopter/Dioptre (unit of measurement) Catoptrics (study of and optical systems utilizing reflection) Catadioptrics (study of and optical systems utilizing reflection and refraction) Optical telescope List of telescope types Image-forming optical system == References ==


id: equatorial-mount-20260505-0
file: data/en.wikipedia.org/wiki/Equatorial_mount-0.md
category: reference
title: Equatorial mount
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Equatorial_mount
date_saved: 2026-05-05T09:47:21.177742+00:00
instance: kb-cron
parent: equatorial-mount-20260505-0
summary:
An equatorial mount is a mount for instruments that compensates for Earth's rotation by having one rotational axis, called polar axis, parallel to the Earth's axis of rotation. This type of mount is used for astronomical telescopes and cameras. The advantage of an equatorial mount lies in its ability to allow the instrument attached to it to stay fixed on any celestial object with diurnal motion by driving one axis at a constant speed. Such an arrangement is called a sidereal drive or clock drive. Equatorial mounts achieve this by aligning their rotational axis with the Earth, a process known as polar alignment. == Astronomical telescope mounts == In astronomical telescope mounts, the equatorial axis (the right ascension) is paired with a second perpendicular axis of motion (known as the declination). The equatorial axis of the mount is often equipped with a motorized "clock drive", that rotates that axis one revolution every 23 hours and 56 minutes in exact sync with the apparent diurnal motion of the sky. They may also be equipped with setting circles to allow for the location of objects by their celestial coordinates. Equatorial mounts differ from mechanically simpler altazimuth mounts, which require variable speed motion


id: equatorial-platform-20260505-0
file: data/en.wikipedia.org/wiki/Equatorial_platform-0.md
category: reference
title: Equatorial platform
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Equatorial_platform
date_saved: 2026-05-05T09:47:22.364105+00:00
instance: kb-cron
parent: equatorial-platform-20260505-0
summary:
An equatorial platform or equatorial table is an equatorial telescope mount in the form of a specially designed platform that allows any device sitting on it to track astronomical objects in the sky on an equatorial axis. They are used to give equatorial tracking to any device sitting on them, from small cameras up to entire observatory buildings. They are often used with altazimuth mounted telescopes, such as the common Dobsonian telescope type, to overcome that type of mount's inability to track the night sky. With careful polar alignment sub-arc second precision CCD imaging is entirely possible. Roeser Observatory, Luxembourg (MPC observatory code 163) have contributed hundreds of astrometric measurements of Near Earth Asteroids to the Minor Planet Center using a home-built 20" Dobsonian telescope on an Osypowski equatorial platform. == Types == Many types of equatorial platform have been used over the years. The mid-1960s saw the introduction of the Russian AFU-75 satellite-tracking camera which consisted of a 3-axis altitude-altitude-azimuth mount mounted on a three-point equatorial platform. Two of the points were aligned on a polar axis while the third was a jackscrew actuator to drive the platform. This gave the mount a few minutes of equatorial tracking to


id: equatorial-room-20260505-0
file: data/en.wikipedia.org/wiki/Equatorial_room-0.md
category: reference
title: Equatorial room
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Equatorial_room
date_saved: 2026-05-05T09:47:23.513200+00:00
instance: kb-cron
parent: equatorial-room-20260505-0
summary:
An equatorial room, in astronomical observatories, is the room which contains an equatorial mounted telescope. It is usually referred to in observatory buildings that contain more than one type of instrument: for example buildings with an "equatorial room" containing an equatorial telescope and a "transit room" containing a transit telescope. Equatorial rooms tend to be large circular rooms to accommodate all the range of motion of a long telescope on an equatorial mount and are usually topped with a dome to keep out the weather. In some cases an observatory would move to a new location, or the equatorial telescope itself would be removed. The space would then be converted, for example, into use as a classroom or library. These peculiar rooms can sometimes be found in buildings at old colleges and towns, with their former use long forgotten. == References == Introduction To Orwell Park Observatory" by James Appleton == Further reading == George Frederick Chambers (1890), A Handbook of Descriptive and Practical Astronomy: Instruments and practical astronomy, Clarendon Press, p. 198 Sir Norman Lockyer (1886), "Detail of the Structure of the Observatory", Nature, XXXIII, Macmillan Journals Limited: 57


id: eyepiece-20260505-0
file: data/en.wikipedia.org/wiki/Eyepiece-0.md
category: reference
title: Eyepiece
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Eyepiece
date_saved: 2026-05-05T09:47:24.682125+00:00
instance: kb-cron
parent: eyepiece-20260505-0
summary:
An eyepiece, or ocular lens, is a type of lens that is attached to a variety of optical devices such as telescopes and microscopes. It is named because it is usually the lens that is closest to the eye when someone looks through an optical device to observe an object or sample. The objective lens or mirror collects light from an object or sample and brings it to focus creating an image of the object. The eyepiece is placed near the focal point of the objective to magnify this image to the eyes. (The eyepiece and the eye together make an image of the image created by the objective, on the retina of the eye.) The amount of magnification depends on the focal length of the eyepiece. An eyepiece consists of several "lens elements" in a housing, with a "barrel" on one end. The barrel is shaped to fit in a special opening of the instrument to which it is attached. The image can be focused by moving the eyepiece nearer and further from the objective. Most instruments have a focusing mechanism to allow movement of the shaft in which the eyepiece is mounted, without needing to manipulate the eyepiece


id: eyepiece-20260505-1
file: data/en.wikipedia.org/wiki/Eyepiece-1.md
category: reference
title: Eyepiece
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Eyepiece
date_saved: 2026-05-05T09:47:24.682125+00:00
instance: kb-cron
parent: eyepiece-20260505-0
summary:
f E {\displaystyle \ f_{\mathsf {E}}\ } is the focal length of the eyepiece. Magnification increases, therefore, when the focal length of the eyepiece is shorter or the focal length of the objective is longer. For example, a 25 mm eyepiece in a telescope with a 1200 mm focal length would magnify objects 48 times. A 4 mm eyepiece in the same telescope would magnify 300 times. Amateur astronomers tend to refer to telescope eyepieces by their focal length in millimeters. These typically range from about 3 mm to 50 mm. Some astronomers, however, prefer to specify the resulting magnification power rather than the focal length. It is often more convenient to express magnification in observation reports, as it gives a more immediate impression of what view the observer actually saw. Due to its dependence on properties of the particular telescope in use, however, magnification power alone is meaningless for describing a telescope eyepiece. For a compound microscope the corresponding formula is M A = D ⋅ D E O f E ⋅ f O = D f E ⋅ D E O f O {\displaystyle \ M_{\mathsf {A}}={\frac {~~~D\ \cdot \ D_{\mathsf {EO}}\ }{\ f_{\mathsf {E}}\ \cdot \ f_{\mathsf


id: eyepiece-20260505-2
file: data/en.wikipedia.org/wiki/Eyepiece-2.md
category: reference
title: Eyepiece
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Eyepiece
date_saved: 2026-05-05T09:47:24.682125+00:00
instance: kb-cron
parent: eyepiece-20260505-0
summary:
True or Telescope's field of view For a telescope or binocular, the actual angular size of the span of sky that can be seen through a particular eyepiece, used with a particular telescope, producing a specific magnification. It ranges typically between 0.1–2 degrees. For a microscope, the actual width of the visible sample on the slide or sample tray, usually given in millimeters, but sometimes given as angular measure, like a telescope. For binoculars it is expressed as the actual field width in feet or in meters at some standard distance (typically either 100 feet or 30 meters, which are very nearly the same: 30 m is only a 2% smaller than 100 feet). Apparent or Eye's field of view For telescopes, microscopes, or binoculars, the apparent field of view is a measure of the angular size of the image seen by the eye, through the eyepiece. In other words, it is how large the image appears (as distinct from the magnification). Unless there is vignetting by the telescope's or microscope's body tube, this is constant for any given eyepiece with a fixed focal length, and may be used to calculate what the true field of view will be when


id: eyepiece-20260505-3
file: data/en.wikipedia.org/wiki/Eyepiece-3.md
category: reference
title: Eyepiece
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Eyepiece
date_saved: 2026-05-05T09:47:24.682125+00:00
instance: kb-cron
parent: eyepiece-20260505-0
summary:
This formula also indicates that, for an eyepiece design with a given apparent field of view, the barrel diameter will determine the maximum focal length possible for that eyepiece, as no field stop can be larger than the barrel itself. For example, a Plössl with 45° apparent field of view in a 1.25 inch barrel would yield a maximum focal length of 35 mm. Anything longer requires larger barrel or the view is restricted by the edge, effectively making the field of view less than 45°. === Barrel diameter === Eyepieces for telescopes and microscopes are usually interchanged to increase or decrease the magnification, and to enable the user to select a type with certain performance characteristics. To allow this, eyepieces come in standardized "Barrel diameters". ==== Telescope eyepieces ==== There are six standard barrel diameters for telescopes. The barrel sizes (usually expressed in inches) are: 0.965 inch (24.5 mm) – This is the smallest standard barrel diameter and is usually found in retail toy store and shopping mall telescopes. Many of these eyepieces that come with such telescopes are plastic, and some even have plastic lenses. High-end telescope eyepieces with this barrel size are no longer manufactured, but you


id: eyepiece-20260505-4
file: data/en.wikipedia.org/wiki/Eyepiece-4.md
category: reference
title: Eyepiece
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Eyepiece
date_saved: 2026-05-05T09:47:24.682125+00:00
instance: kb-cron
parent: eyepiece-20260505-0
summary:
A simple convex lens placed after the focus of the objective lens presents the viewer with a magnified inverted image. This configuration may have been used in the first refracting telescopes from the Netherlands and was proposed as a way to have a much wider field of view and higher magnification in telescopes in Johannes Kepler's 1611 book Dioptrice. Since the lens is placed after the focal plane of the objective it also allowed for use of a micrometer at the focal plane (used for determining the angular size and/or distance between objects observed). === Huygens === Huygens eyepieces consist of two plano-convex lenses with the plane sides towards the eye separated by an air gap. The lens closest to an observer's eye is called the eye lens and the other lens is called field lens. The focal plane is located between the two lenses. It was invented by Christiaan Huygens in the late 1660s and was the first compound (multi-lens) eyepiece. Huygens discovered that two air spaced lenses can be used to make an eyepiece with zero transverse chromatic aberration. If the lenses are made of glass of the same Abbe number, to be used with a relaxed eye


id: eyepiece-20260505-5
file: data/en.wikipedia.org/wiki/Eyepiece-5.md
category: reference
title: Eyepiece
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Eyepiece
date_saved: 2026-05-05T09:47:24.682125+00:00
instance: kb-cron
parent: eyepiece-20260505-0
summary:
=== Orthoscopic or "Abbe" === The 4-element orthoscopic eyepiece consists of a plano-convex singlet eye lens and a cemented convex-convex triplet field lens achromatic field lens. This gives the eyepiece a nearly perfect image quality and good eye relief, but a narrow apparent field of view — about 40°–45°. It was invented by Ernst Abbe in 1880. It is called "orthoscopic" or "orthographic" because of its low degree of distortion and is also sometimes called an "ortho" or "Abbe". Until the advent of multicoating and the popularity of the Plössl, orthoscopic eyepieces were the most popular design for telescope eyepieces. Even today these eyepieces are considered good eyepieces for planetary and lunar viewing. They are preferred for reticle eyepieces, since they are one of the wide-field, long eye-relief designs with an external focal plane; slowly being supplanted by the König. Due to their low degree of distortion and the corresponding globe effect, they are less suitable for applications which require an extensive panning of the instrument. === Monocentric === A Monocentric is an achromatic triplet lens with two pieces of crown glass cemented on both sides of a flint glass element. The elements are thick, strongly curved, and their surfaces


id: eyepiece-20260505-6
file: data/en.wikipedia.org/wiki/Eyepiece-6.md
category: reference
title: Eyepiece
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Eyepiece
date_saved: 2026-05-05T09:47:24.682125+00:00
instance: kb-cron
parent: eyepiece-20260505-0
summary:
Invented by Albert Nagler and patented in 1979, the Nagler eyepiece is a design optimized for astronomical telescopes to give an ultra-wide field of view (82°) that has good correction for astigmatism and other aberrations. Introduced in 2007, the Ethos is an enhanced ultra-wide field design developed principally by Paul Dellechiaie under Albert Nagler's guidance at TeleVue Optics and claims a 100–110° AFOV. This is achieved using exotic high-index glass and up to eight optical elements in four or five groups; there are several similar designs called the Nagler, Nagler type 2, Nagler type 4, Nagler type 5, and Nagler type 6. The newer Delos design is a modified Ethos design with a FOV of 'only' 72 degrees but with a long 20 mm eye relief. The number of elements in a Nagler makes them seem complex, but the idea of the design is fairly simple: every Nagler has a negative doublet field lens, which increases magnification, followed by several positive groups. The positive groups, considered separate from the first negative group, combine to have long focal length, and form a positive lens. That allows the design to take advantage of the many good qualities of low power lenses. In


id: farside-telescope-20260505-0
file: data/en.wikipedia.org/wiki/FARSIDE_telescope-0.md
category: reference
title: FARSIDE telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/FARSIDE_telescope
date_saved: 2026-05-05T09:47:25.858959+00:00
instance: kb-cron
parent: farside-telescope-20260505-0
summary:
FARSIDE (Farside Array for Radio Science Investigations of the Dark Ages and Exoplanets) is a concept for a low-frequency interferometric array that would be placed on the farside of the Moon. == FarView == FarView is another concept for a 20x20 km radio observatory with a total collecting area of 400 kilometers that would also be located on the Moon's far side. == References ==


id: first-light-astronomy-20260505-0
file: data/en.wikipedia.org/wiki/First_light_(astronomy)-0.md
category: reference
title: First light (astronomy)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/First_light_(astronomy)
date_saved: 2026-05-05T09:47:26.973345+00:00
instance: kb-cron
parent: first-light-astronomy-20260505-0
summary:
In astronomy, first light is the first practical use of a new instrument, typically a telescope to take an astronomical image after it has been constructed. This is often not the first viewing using the telescope because optical tests have likely been performed to adjust the components. == See also == First light (cosmology) == References ==


id: foucault-knife-edge-test-20260505-0
file: data/en.wikipedia.org/wiki/Foucault_knife-edge_test-0.md
category: reference
title: Foucault knife-edge test
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Foucault_knife-edge_test
date_saved: 2026-05-05T09:47:28.166765+00:00
instance: kb-cron
parent: foucault-knife-edge-test-20260505-0
summary:
The Foucault knife-edge test is an optical test to accurately measure the shape of concave curved mirrors. It is commonly used by amateur telescope makers for figuring primary mirrors in reflecting telescopes. It uses a relatively simple, inexpensive apparatus compared to other testing techniques. == Overview == The Foucault knife-edge test was described in 1858 by French physicist Léon Foucault as a way to measure conic shapes of optical mirrors. It measures mirror surface dimensions by reflecting light into a knife edge at or near the mirror's centre of curvature. In doing so, it only needs a tester which in its most basic 19th century form consists of a light bulb, a piece of tinfoil with a pinhole in it, and a razor blade to create the knife edge. The testing device is adjustable along the X-axis (knife cut direction) across the Y-axis (optical axis), and is usually equipped with measurable adjustment to 0.001 inch (25 μm) or better along lines parallel to the optical axis. The test can measure errors in a mirror's curvature to fractions of wavelengths of light (or Angstroms, millionths of an inch, or nanometers). == Foucault test basics == Foucault testing is commonly used by


id: galaxy-h-alpha-fabry-perot-system-20260505-0
file: data/en.wikipedia.org/wiki/Galaxy_H-Alpha_Fabry-Perot_System-0.md
category: reference
title: Galaxy H-Alpha Fabry-Perot System
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Galaxy_H-Alpha_Fabry-Perot_System
date_saved: 2026-05-05T09:47:29.348978+00:00
instance: kb-cron
parent: galaxy-h-alpha-fabry-perot-system-20260505-0
summary:
The Galaxy Hα Fabry-Perot System for WHT (GHaFaS) is an astronomical instrument installed on the 4.2 metre William Herschel Telescope (WHT) at Roque de los Muchachos Observatory on the Canary island of La Palma. First light was on 6 July 2007. Its name is a play on the acronym: Galaxy Hα Fabry-Perot System and the Spanish word "gafas" meaning spectacles. It produces maps, in intensity and velocity, of extended objects in the sky (which could be external galaxies, star forming regions in the Galaxy, planetary nebulae, or supernova remnants, as examples), which radiate in the H-alpha line, emitted by ionized hydrogen in interstellar space. It can also be used for a variety of other lines. The possibility to detect the emission line of interstellar neutral hydrogen at 21 centimeters wavelength revolutionized astronomy in the second half of the 20th century, as a powerful tool to explore the structure and evolution of galaxies and the star formation within them. A second revolution came, when, at millimetre wavelengths, molecular hydrogen could be detected and measured in directly using, above all, the emission from the lines of the CO molecule. Surprisingly, the emission from the third phase of interstellar hydrogen, the ionized phase,


id: goto-telescopes-20260505-0
file: data/en.wikipedia.org/wiki/GoTo_(telescopes)-0.md
category: reference
title: GoTo (telescopes)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/GoTo_(telescopes)
date_saved: 2026-05-05T09:47:30.542717+00:00
instance: kb-cron
parent: goto-telescopes-20260505-0
summary:
In amateur astronomy, "GoTo" refers to a type of telescope mount and related software that can automatically point a telescope at astronomical objects that the user selects. Both axes of a GoTo mount are driven by a motor and controlled by a computer. It may be either a microprocessor-based integrated controller or an external personal computer. This differs from the single-axis semi-automated tracking of a traditional clock-drive equatorial mount. The user can command the mount to point the telescope to the celestial coordinates that the user inputs, or to objects in a pre-programmed database including ones from the Messier catalogue, the New General Catalogue, and even major Solar System bodies (the Sun, Moon, and planets). Like a standard equatorial mount, equatorial GoTo mounts can track the night sky by driving the right ascension axis. Since both axes are computer controlled, GoTo technology also allows telescope manufacturers to add equatorial tracking to mechanically simpler altazimuth mounts. == How a GoTo mount works == GoTo mounts are pre-aligned before use. When it is powered on, it may ask for the user's latitude, longitude, time, and date. It can also get this data from a GPS receiver connected to the telescope or built


id: greenland-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Greenland_Telescope-0.md
category: reference
title: Greenland Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Greenland_Telescope
date_saved: 2026-05-05T09:47:31.746296+00:00
instance: kb-cron
parent: greenland-telescope-20260505-0
summary:
The Greenland Telescope is a radio telescope situated at the Pituffik Space Base in north-western Greenland. It will later be deployed at the Summit Station research camp, located at the highest point of the Greenland ice sheet at an altitude of 3,210 meters (10,530 feet). The telescope is an international collaboration between: The Academia Sinica Institute of Astronomy and Astrophysics (Taiwan) (project leaders) The Smithsonian Astrophysical Observatory of the Center for Astrophysics | Harvard & Smithsonian (United States) The National Radio Astronomy Observatory (United States) The Haystack Observatory of the Massachusetts Institute of Technology (United States) In 2011 the U.S. National Science Foundation gave the Smithsonian Astrophysical Observatory a 12-meter radio antenna that had been used as a prototype for the ALMA project in Chile. The antenna was to be deployed in Greenland. Deploying the telescope in the middle of Greenland is ideal for detecting certain radio frequencies. The telescope will be used to study the event horizons of black holes and to test how general relativity behaves in environments with extreme gravity. The Greenland Telescope will become part of the global network of telescopes that makes up the Event Horizon Telescope that will study supermassive black holes and explore


id: hale-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Hale_Telescope-0.md
category: reference
title: Hale Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hale_Telescope
date_saved: 2026-05-05T09:47:32.989856+00:00
instance: kb-cron
parent: hale-telescope-20260505-0
summary:
The Hale Telescope is a 200-inch (5.1 m), f/3.3 reflecting telescope at the Palomar Observatory in San Diego County, California, US, named after astronomer George Ellery Hale. With funding from the Rockefeller Foundation in 1928, he orchestrated the planning, design, and construction of the observatory, but with the project ending up taking 20 years he did not live to see its commissioning. The Hale was groundbreaking for its time, with double the diameter of the second-largest telescope, and pioneered many new technologies in telescope mount design and in the design and fabrication of its large aluminum coated "honeycomb" low thermal expansion Pyrex mirror. It was completed in 1949 and is still in active use. The Hale Telescope represented the technological limit in building large optical telescopes for over 30 years. It was the largest telescope in the world from its construction in 1949 until the Soviet BTA-6 was built in 1976, and the second largest until the construction of the Keck Observatory Keck 1 in Hawaii in 1993. == History == Hale supervised the building of the telescopes at the Mount Wilson Observatory with grants from the Carnegie Institution of Washington: the 60-inch (1.5 m) telescope in 1908 and the


id: hale-telescope-20260505-1
file: data/en.wikipedia.org/wiki/Hale_Telescope-1.md
category: reference
title: Hale Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hale_Telescope
date_saved: 2026-05-05T09:47:32.989856+00:00
instance: kb-cron
parent: hale-telescope-20260505-0
summary:
The mirror was cast in a mold with 36 raised mold blocks (similar in shape to a waffle iron). This created a honeycomb mirror that cut the amount of Pyrex needed down from over 40 short tons (36 t) to just 20 short tons (18 t), making a mirror that would cool faster in use and have multiple "mounting points" on the back to evenly distribute its weight (note – see external links 1934 article for drawings). The shape of a central hole was also part of the mold so light could pass through the finished mirror when it was used in a Cassegrain configuration (a Pyrex plug for this hole was also made to be used during the grinding and polishing process). While the glass was being poured into the mold during the first attempt to cast the 200-inch mirror, the intense heat caused several of the molding blocks to break loose and float to the top, ruining the mirror. The defective mirror was used to test the annealing process. After the mold was re-engineered, a second mirror was successfully cast. After cooling several months, the finished mirror blank was transported by rail to Pasadena, California. Once in Pasadena


id: hartmann-mask-20260505-0
file: data/en.wikipedia.org/wiki/Hartmann_mask-0.md
category: reference
title: Hartmann mask
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hartmann_mask
date_saved: 2026-05-05T09:47:34.180616+00:00
instance: kb-cron
parent: hartmann-mask-20260505-0
summary:
Hartmann mask is a tool to help focusing telescopes, mainly used by amateur astronomers. It is named after the German astronomer Johannes Franz Hartmann (1865–1936), who developed it around 1900. == History == Hartmann mask was invented as a tool to check the quality of large optical mirrors. It was especially useful for large non-spherical mirrors for telescopes. For example, the illustration on the right shows the Hartmann mask used to test the Hale Telescope five-meter primary mirror. In today's professional telescope making, it has been completely superseded by interferometric methods. == Theory and practice == Every part of a mirror or lens produces the same image as the whole optical element. The light is focused in the focal point. The light rays, however, go through different points of a plane before or behind the focus. This phenomenon can be used when focusing a telescope. The Hartmann mask is a simple opaque mask containing two or three holes. (This device is called a Hartmann mask if it has multiple holes, or a Scheiner disk if it has two holes.) The mask covers the aperture of the telescope. When the apparatus is out of focus, multiple images can be seen if


id: hatnet-project-20260505-0
file: data/en.wikipedia.org/wiki/HATNet_Project-0.md
category: reference
title: HATNet Project
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/HATNet_Project
date_saved: 2026-05-05T09:47:35.525770+00:00
instance: kb-cron
parent: hatnet-project-20260505-0
summary:
The Hungarian Automated Telescope Network (HATNet) project is a network of six small fully automated "HAT" telescopes. The scientific goal of the project is to detect and characterize extrasolar planets using the transit method. This network is used also to find and follow bright variable stars. The network is maintained by the Center for Astrophysics | Harvard & Smithsonian. The HAT acronym stands for Hungarian-made Automated Telescope, because it was developed by a small group of Hungarians who met through the Hungarian Astronomical Association. The project started in 1999 and has been fully operational since May 2001. == Equipment == The prototype instrument, HAT-1 was built from a 180 mm focal length and 65 mm aperture Nikon telephoto lens and a Kodak KAF-0401E chip of 512 × 768, 9 μm pixels. The test period was from 2000 to 2001 at the Konkoly Observatory in Budapest. HAT-1 was transported from Budapest to the Steward Observatory, Kitt Peak, Arizona, USA, in January 2001. The transportation caused serious damage to the equipment. Later built telescopes use Canon 11 cm diameter f/1.8L lenses for a wide-field of 8°×8°. It is a fully automated instrument with 2K x 2K Charge-coupled device (CCD) sensors. One HAT


id: hexapod-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Hexapod-Telescope-0.md
category: reference
title: Hexapod-Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hexapod-Telescope
date_saved: 2026-05-05T09:47:36.717215+00:00
instance: kb-cron
parent: hexapod-telescope-20260505-0
summary:
The Hexapod-Telescope (HPT) was a 1.5-metre (59 in) Ritchey-Chrétien optical telescope, that operated in 2006-2017 in the Cerro Armazones Observatory (OCA) in northern Chile, and is currently decommissioned. The notable feature of the HPT – and the reason for its name – was the design of its mount. Instead of the typical mounting where the telescope moves on two rotating axes, the mirror cell was supported by six extensible (variable-length) struts, an arrangement known as a Stewart platform. This configuration allowed the telescope to move in all six spatial degrees of freedom and provided strong structural integrity. Furthermore, the six-leg structure allowed for a very precise positioning and repeatability. The HPT could have been rotated ±45° around the optical axis in any position. The mount allowed observations up to 30° elevation. Additionally, by using carbon fiber composites, the HPT was lighter by a factor of ten than classical telescopes of the same aperture. As a result, the ratio of bearing pressure and its own weight was very high. The active primary mirror had a diameter of 1.5 meters and – with a thickness of only 50 mm – was mounted on 36 piezo actuators. The secondary mirror was also supported


id: history-of-the-telescope-20260505-0
file: data/en.wikipedia.org/wiki/History_of_the_telescope-0.md
category: reference
title: History of the telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_the_telescope
date_saved: 2026-05-05T09:47:38.014297+00:00
instance: kb-cron
parent: history-of-the-telescope-20260505-0
summary:
The history of the telescope can be traced to before the invention of the earliest known telescope, which appeared in 1608 in the Netherlands, when a patent was submitted by Hans Lippershey, an eyeglass maker. Although Lippershey did not receive his patent, news of the invention soon spread across Europe. The design of these early refracting telescopes consisted of a convex objective lens and a concave eyepiece. Galileo improved on this design the following year and applied it to astronomy. In 1611, Johannes Kepler described how a far more useful telescope could be made with a convex objective lens and a convex eyepiece lens. By 1655, astronomers such as Christiaan Huygens were building powerful but unwieldy Keplerian telescopes with compound eyepieces. Isaac Newton is credited with building the first reflector in 1668 with a design that incorporated a small flat diagonal mirror to reflect the light to an eyepiece mounted on the side of the telescope. Laurent Cassegrain in 1672 described the design of a reflector with a small convex secondary mirror to reflect light through a central hole in the main mirror. The achromatic lens, which greatly reduced color aberrations in objective lenses and allowed for shorter and more


id: history-of-the-telescope-20260505-1
file: data/en.wikipedia.org/wiki/History_of_the_telescope-1.md
category: reference
title: History of the telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_the_telescope
date_saved: 2026-05-05T09:47:38.014297+00:00
instance: kb-cron
parent: history-of-the-telescope-20260505-0
summary:
In 1655, the Dutch diplomat William de Boreel tried to solve the mystery of who invented the telescope. He had a local magistrate in Middelburg follow-up on Boreel's childhood and early adult recollections of a spectacle-maker named "Hans", who he remembered as the inventor of the telescope. The magistrate was contacted by a then-unknown claimant– the Middelburg spectacle-maker Johannes Zachariassen, who testified that his father– Zacharias Janssen, invented the telescope and the microscope as early as 1590. This testimony seemed convincing to Boreel, who now recollected that Zacharias and his father– Hans Martens, must have been who he remembered. Boreel's conclusion that Zacharias Janssen invented the telescope a little ahead of another spectacle maker, Hans Lippershey, was adopted by Pierre Borel in his 1656 book De vero telescopii inventore. Discrepancies in Boreel's investigation and Zachariassen's testimony (including Zachariassen misrepresenting his date of birth and role in the invention) has led some historians to consider this claim dubious. The "Janssen" claim would continue over the years and be added on to with Zacharias Snijder in 1841 presenting 4 iron tubes with lenses in them claimed to be 1590 examples of Janssen's telescope and historian Cornelis de Waard's 1906 claim that the


id: history-of-the-telescope-20260505-2
file: data/en.wikipedia.org/wiki/History_of_the_telescope-2.md
category: reference
title: History of the telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_the_telescope
date_saved: 2026-05-05T09:47:38.014297+00:00
instance: kb-cron
parent: history-of-the-telescope-20260505-0
summary:
Galileo set himself to improving the telescope, producing telescopes of increased magnification. His first telescope had a 3x magnification, but he soon made instruments which magnified 8x, and finally, one nearly a meter long with a 37mm objective (which he would stop down to 16mm or 12mm) and a 23x magnification. With this last instrument, he began a series of astronomical observations in October or November 1609, observing the satellites of Jupiter, hills and valleys on the moon, the phases of Venus and spots on the sun (using the projection method rather than direct observation). Galileo noted that the revolution of the satellites of Jupiter, the phases of Venus, rotation of the sun and the tilted path its spots followed for part of the year pointed to the validity of the sun-centered Copernican system over other Earth-centered systems such as the one proposed by Ptolemy. Galileo's instrument was the first to be given the name "telescope". The name was invented by the Greek poet/theologian Giovanni Demisiani at a banquet held on April 14, 1611, by Prince Federico Cesi to make Galileo Galilei a member of the Accademia dei Lincei. The word was created from the Greek tele = 'far' and


id: history-of-the-telescope-20260505-3
file: data/en.wikipedia.org/wiki/History_of_the_telescope-3.md
category: reference
title: History of the telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_the_telescope
date_saved: 2026-05-05T09:47:38.014297+00:00
instance: kb-cron
parent: history-of-the-telescope-20260505-0
summary:
In 1636 Marin Mersenne proposed a telescope consisting of a paraboloidal primary mirror and a paraboloidal secondary mirror bouncing the image through a hole in the primary, solving the problem of viewing the image. James Gregory went into further detail in his book Optica Promota (1663), pointing out that a reflecting telescope with a mirror that was shaped like the part of a conic section, would correct spherical aberration as well as the chromatic aberration seen in refractors. The design he came up with bears his name: the "Gregorian telescope"; but according to his own confession, Gregory had no practical skill and he could find no optician capable of realizing his ideas and after some fruitless attempts, was obliged to abandon all hope of bringing his telescope into practical use. In 1666 Isaac Newton, based on his theories of refraction and color, perceived that the faults of the refracting telescope were due more to a lens's varying refraction of light of different colors than to a lens's imperfect shape. He concluded that light could not be refracted through a lens without causing chromatic aberrations, although he incorrectly concluded from some rough experiments that all refracting substances would diverge the prismatic


id: history-of-the-telescope-20260505-4
file: data/en.wikipedia.org/wiki/History_of_the_telescope-4.md
category: reference
title: History of the telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_the_telescope
date_saved: 2026-05-05T09:47:38.014297+00:00
instance: kb-cron
parent: history-of-the-telescope-20260505-0
summary:
About the year 1774 William Herschel (then a teacher of music in Bath, England) began to occupy his leisure hours with the construction of reflector telescope mirrors, finally devoted himself entirely to their construction and use in astronomical research. In 1778, he selected a 6+1⁄4-inch (16 cm) reflector mirror (the best of some 400 telescope mirrors which he had made) and with it, built a 7-foot (2.1 m) focal length telescope. Using this telescope, he made his early brilliant astronomical discoveries. In 1783, Herschel completed a reflector of approximately 18 inches (46 cm) in diameter and 20 ft (6.1 m) focal length. He observed the heavens with this telescope for some twenty years, replacing the mirror several times. In 1789 Herschel finished building his largest reflecting telescope with a mirror of 49 inches (120 cm) and a focal length of 40 ft (12 m), (commonly known as his 40-foot telescope) at his new home, at Observatory House in Slough, England. To cut down on the light loss from the poor reflectivity of the speculum mirrors of that day, Herschel eliminated the small diagonal mirror from his design and tilted his primary mirror so he could view the formed image directly.


id: history-of-the-telescope-20260505-5
file: data/en.wikipedia.org/wiki/History_of_the_telescope-5.md
category: reference
title: History of the telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_the_telescope
date_saved: 2026-05-05T09:47:38.014297+00:00
instance: kb-cron
parent: history-of-the-telescope-20260505-0
summary:
From the time of the invention of the first refracting telescopes it was generally supposed that chromatic errors seen in lenses simply arose from errors in the spherical figure of their surfaces. Opticians tried to construct lenses of varying forms of curvature to correct these errors. Isaac Newton discovered in 1666 that chromatic colors actually arose from the un-even refraction of light as it passed through the glass medium. This led opticians to experiment with lenses constructed of more than one type of glass in an attempt to canceling the errors produced by each type of glass. It was hoped that this would create an "achromatic lens"; a lens that would focus all colors to a single point, and produce instruments of much shorter focal length. The first person who succeeded in making a practical achromatic refracting telescope was Chester Moore Hall from Essex, England. He argued that the different humours of the human eye refract rays of light to produce an image on the retina which is free from color, and he reasonably argued that it might be possible to produce a like result by combining lenses composed of different refracting media. After devoting some time to the inquiry


id: history-of-the-telescope-20260505-6
file: data/en.wikipedia.org/wiki/History_of_the_telescope-6.md
category: reference
title: History of the telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_the_telescope
date_saved: 2026-05-05T09:47:38.014297+00:00
instance: kb-cron
parent: history-of-the-telescope-20260505-0
summary:
As a practical man, Dollond at once put his doubts to the test of experiment: he confirmed the conclusions of Klingenstierna, discovered a difference far beyond his hopes in the refractive qualities of different kinds of glass with respect to the divergence of colors, and was thus rapidly led to the construction of lenses in which first the chromatic aberration—and afterwards—the spherical aberration were corrected. Dollond was aware of the conditions necessary for the attainment of achromatism in refracting telescopes, but relied on the accuracy of experiments made by Newton. His writings show that with the exception of his bravado, he would have arrived sooner at a discovery for which his mind was fully prepared. Dollond's paper recounts the successive steps by which he arrived at his discovery independently of Hall's earlier invention—and the logical processes by which these steps were suggested to his mind. In 1765 Peter Dollond (son of John Dollond) introduced the triple objective, which consisted of a combination of two convex lenses of crown glass with a concave flint lens between them. He made many telescopes of this kind. The difficulty of procuring disks of glass (especially of flint glass) of suitable purity and homogeneity limited


id: history-of-the-telescope-20260505-7
file: data/en.wikipedia.org/wiki/History_of_the_telescope-7.md
category: reference
title: History of the telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_the_telescope
date_saved: 2026-05-05T09:47:38.014297+00:00
instance: kb-cron
parent: history-of-the-telescope-20260505-0
summary:
Adaptive optics uses a similar principle, but applying corrections several hundred times per second to compensate the effects of rapidly changing optical distortion due to the motion of turbulence in Earth's atmosphere. Adaptive optics works by measuring the distortions in a wavefront and then compensating for them by rapid changes of actuators applied to a small deformable mirror or with a liquid crystal array filter. AO was first envisioned by Horace W. Babcock in 1953, but did not come into common usage in astronomical telescopes until advances in computer and detector technology during the 1990s made it possible to calculate the compensation needed in real time. In adaptive optics, the high-speed corrections needed mean that a fairly bright star is needed very close to the target of interest (or an artificial star is created by a laser). Also, with a single star or laser the corrections are only effective over a very narrow field (tens of arcsec), and current systems operating on several 8-10m telescopes work mainly in near-infrared wavelengths for single-object observations. Developments of adaptive optics include systems with multiple lasers over a wider corrected field, and/or working above kiloHertz rates for good correction at visible wavelengths; these are


id: history-of-the-telescope-20260505-8
file: data/en.wikipedia.org/wiki/History_of_the_telescope-8.md
category: reference
title: History of the telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_the_telescope
date_saved: 2026-05-05T09:47:38.014297+00:00
instance: kb-cron
parent: history-of-the-telescope-20260505-0
summary:
X-rays from space do not reach Earth's surface, so X-ray astronomy must be conducted above Earth's atmosphere. The first X-ray experiments were conducted on sub-orbital rocket flights, which enabled the first detection of X-rays from the sun (1948), and then from the first galactic X-ray sources: Scorpius X-1 (June 1962) and the Crab Nebula (October 1962). Since then, X-ray telescopes (Wolter telescopes) have been built using nested grazing-incidence mirrors which deflect X-rays to a detector. Some of the OAO satellites conducted X-ray astronomy in the late 1960s, but the first dedicated X-ray satellite was the Uhuru (1970) which discovered 300 sources. More recent X-ray satellites include: the EXOSAT (1983), ROSAT (1990), Chandra (1999), and Newton (1999). === Gamma-ray telescopes (less than 0.01 nm) === Gamma rays are absorbed high in Earth's atmosphere, so most gamma-ray astronomy is conducted with satellites. Gamma-ray telescopes use scintillation counters, spark chambers and more recently, solid-state detectors. The angular resolution of these devices is typically very poor. There were balloon-borne experiments in the early 1960s, but gamma-ray astronomy really began with the launch of the OSO 3 satellite in 1967; the first dedicated gamma-ray satellites were SAS B (1972) and Cos B (1975). The Compton


id: history-of-the-telescope-20260505-9
file: data/en.wikipedia.org/wiki/History_of_the_telescope-9.md
category: reference
title: History of the telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_the_telescope
date_saved: 2026-05-05T09:47:38.014297+00:00
instance: kb-cron
parent: history-of-the-telescope-20260505-0
summary:
== External links == History of optics articles Best Idea; Eyes Wide Open History of telescope articles The Galileo Project – The Telescope by Al Van Helden 400th Anniversary of the Invention of the Telescope Archived 2010-04-25 at the Wayback Machine Articles on the history of the telescope and related subjects Archived 2012-03-17 at the Wayback Machine The Prehistory of the Invention of the Telescope A Brief History of the Telescope and Ideas for Use in the High School Physics Classroom A History Of The Telescope Physics 1040 – Beginning Astronomy – The Telescope An early history of the telescope – From 3500 B.C. until about 1900 A.D. Reflecting telescopes Historical Introduction – The Early Period (1608–1672) Other media Eyes on the Skies - documentary available online about the history and future of the telescope Archived 2015-02-24 at the Wayback Machine Other possible telescope inventors Leonard Digges (1520–1559) Did the reflecting telescope have English origins? Leonard and Thomas Digges by Colin A Ronan, M.Sc., F.R.A.S. - originally published in the Journal of the British Astronomical Association, 101, 6, 1991 Archived 2004-10-29 at the Wayback Machine Juan Roget (died before 1624) – Historian Nick Pelling says Juan Roget, a Burgundian spectacle


id: image-forming-optical-system-20260505-0
file: data/en.wikipedia.org/wiki/Image-forming_optical_system-0.md
category: reference
title: Image-forming optical system
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Image-forming_optical_system
date_saved: 2026-05-05T09:47:39.202911+00:00
instance: kb-cron
parent: image-forming-optical-system-20260505-0
summary:
In optics, an image-forming optical system is a system capable of being used for imaging. The diameter of the aperture of the main objective is a common criterion for comparison among optical systems, such as large telescopes. The two traditional optical systems are mirror-systems (catoptrics) and lens-systems (dioptrics). However, in the late twentieth century, optical fiber was introduced as a technology for transmitting images over long distances. Catoptrics and dioptrics have a focal point that concentrates light onto a specific point, while optical fiber the transfer of an image from one plane to another without the need for an optical focus. Isaac Newton is reported to have designed what he called a catadioptrical phantasmagoria, which can be interpreted to mean an elaborate structure of both mirrors and lenses. Catoptrics and optical fiber have no chromatic aberration, while dioptrics need to have this error corrected. Newton believed that such correction was impossible, because he thought the path of the light depended only on its color. In 1757 John Dollond made an achromatised dioptric, which was the forerunner of the lenses used in all popular photographic equipment today. Lower-energy X-rays are the highest-energy electromagnetic radiation that can be focused into an image,


id: infinite-axis-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Infinite-axis_telescope-0.md
category: reference
title: Infinite-axis telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Infinite-axis_telescope
date_saved: 2026-05-05T09:47:40.372231+00:00
instance: kb-cron
parent: infinite-axis-telescope-20260505-0
summary:
An infinite-axis telescope is a telescope that can move freely in all directions. Such telescopes can be mechanically simple hand-guided versions with the mounting serving only to carry the weight of the telescope although there are equatorial versions. == Types == An example of this type of telescope was the late 17th century "Air" or "Aerial telescope", which was a very long focal length refracting telescope that did not use a tube. In these telescopes a hand held eyepiece and an objective mounted on a ball joint were connected by a string; the observer kept the string tight and moved the eyepiece to aim the telescope. Another example of an infinite-axis telescope is a ball-in-cup mounted telescope, also called a spherical-mounted telescope. The first Newtonian telescope was mounted in this way; the ball was held in place by wrought iron springs. Another type uses a bowling balls as a mount axis. There are modern commercial and amateur mount designs for Newtonian telescopes that have the "ball" built into the base of the optical tube assembly. These mounts have the advantage of being mechanically simple and allow the observer to rotate the eyepiece to any side of the telescope for easier


id: integral-field-spectrograph-20260505-0
file: data/en.wikipedia.org/wiki/Integral_field_spectrograph-0.md
category: reference
title: Integral field spectrograph
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Integral_field_spectrograph
date_saved: 2026-05-05T09:47:41.610438+00:00
instance: kb-cron
parent: integral-field-spectrograph-20260505-0
summary:
Integral field spectrographs (IFS) combine spectrographic and imaging capabilities in the optical or infrared wavelength domains (0.32 μm – 24 μm) to get from a single exposure spatially resolved spectra in a bi-dimensional region. The name originates from the fact that the measurements result from integrating the light on multiple sub-regions of the field. Developed at first for the study of astronomical objects, this technique is now also used in many other fields, such as bio-medical science and Earth remote sensing. Integral field spectrography is part of the broader category of snapshot hyperspectral imaging techniques, itself a part of hyperspectral imaging. == Rationale == With the notable exception of individual stars, most astronomical objects are spatially resolved by large telescopes. For spectroscopic studies, the optimum would then be to get a spectrum for each spatial pixel in the instrument field of view, getting full information on each target. This is loosely called a datacube from its two spatial and one spectral dimensions. Since both visible charge-coupled devices (CCD) and infrared detector arrays (staring arrays) used for astronomical instruments are bi-dimensional only, it is a non-trivial feat to develop spectrographic systems able to deliver 3D data cubes from the output of


id: integral-field-spectrograph-20260505-1
file: data/en.wikipedia.org/wiki/Integral_field_spectrograph-1.md
category: reference
title: Integral field spectrograph
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Integral_field_spectrograph
date_saved: 2026-05-05T09:47:41.610438+00:00
instance: kb-cron
parent: integral-field-spectrograph-20260505-0
summary:
=== Fiber array === The sky image given by the telescope falls on a fiber-based image slicer. It is typically made of a few thousands fibers each about 0.1 mm diameter, with the square or circular input field reformatted into a narrow rectangular (long-slit-like) output. The image slicer output is then coupled to a classical long-slit spectrograph that delivers the datacubes. A sky demonstrator successfully undertook the first Fiber based IFS observation in 1990. It was followed by the full-fledged SILFID optical instrument some 5 years later. Coupling the circular fibers to a square or hexagonal lenslet array led to better light injection in the fiber and a nearly 100% filling factor of sky light. Pros are 100% on-sky spatial filling, an efficient use of detector pixels and commercially available fiber-based image slicers. Cons are the sizable light loss in the fibers (~ 25%), their relatively poor photometric accuracy and their inability to work in a cryogenic environment. The latter limits wavelength coverage to less than 1.6 μm. This technique is used by instruments in many telescopes (such as INTEGRAL at the William Herschel Telescope), and particularly in currently ongoing large surveys of galaxies, such as the Calar Alto Legacy


id: integral-field-spectrograph-20260505-2
file: data/en.wikipedia.org/wiki/Integral_field_spectrograph-2.md
category: reference
title: Integral field spectrograph
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Integral_field_spectrograph
date_saved: 2026-05-05T09:47:41.610438+00:00
instance: kb-cron
parent: integral-field-spectrograph-20260505-0
summary:
One such approach was used by the SDSS MaNGA program, Mapping Nearby Galaxies at Apache Point Observatory. MaNGA used IFUs composed of hexagonal fiber bundles to survey about ~10,000 nearby galaxies around redshift 0.03, studying their dynamical state, composition, and formation history. MaNGA was able to use 17 IFU fiber bundles per spectroscopic plate, efficiently targeting many objects simultaneously. A clever alternative approach to obtaining spatially resolved spectroscopy of many objects simultaneously is the MSA-3D program which uses the micro-shutter array of the JWST NIRSpec instrument to target many objects simultaneously. While not strictly an integral-field unit, the MSA-3D program takes many exposures while "stepping" the conventional slitmask provided by the MSA across the sky. These exposures can be combined after the fact to provide full, 3D spatial and spectral information on each object. While the MSA-3D approach provides much lower spatial resolution than the IFU provided with NIRSpec, and requires many more exposures, it has the advantage of being able to target dozens of nearby objects simultaneously. Even larger latitude in the choice of coverage of the patrol field has been proposed under the name of Diverse Field Spectroscopy (DFS) which would allow the observer to select arbitrary combinations


id: intensity-interferometer-20260505-0
file: data/en.wikipedia.org/wiki/Intensity_interferometer-0.md
category: reference
title: Intensity interferometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Intensity_interferometer
date_saved: 2026-05-05T09:47:42.763419+00:00
instance: kb-cron
parent: intensity-interferometer-20260505-0
summary:
An intensity interferometer is the name given to devices that use the Hanbury Brown and Twiss effect. In astronomy, the most common use of such an astronomical interferometer is to determine the apparent diameter of a radio source or star. If the distance to the object can then be determined by parallax or some other method, the physical diameter of the star can then be inferred. An example of an optical intensity interferometer is the Narrabri Stellar Intensity Interferometer. In quantum optics, some devices which take advantage of correlation and anti-correlation effects in beams of photons might be said to be intensity interferometers, although the term is usually reserved for observatories. An intensity interferometer is built from two light detectors, typically either radio antenna or optical telescopes with photomultiplier tubes (PMTs), separated by some distance, called the baseline. Both detectors are pointed at the same astronomical source, and intensity measurements are then transmitted to a central correlator facility. A major advantage of intensity interferometers is that only the measured intensity observed by each detector must be sent to the central correlator facility, rather than the amplitude and phase of the signal. The intensity interferometer measures interferometric visibilities like all other


id: international-liquid-mirror-telescope-20260505-0
file: data/en.wikipedia.org/wiki/International_Liquid_Mirror_Telescope-0.md
category: reference
title: International Liquid Mirror Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/International_Liquid_Mirror_Telescope
date_saved: 2026-05-05T09:47:43.937211+00:00
instance: kb-cron
parent: international-liquid-mirror-telescope-20260505-0
summary:
The International Liquid Mirror Telescope is a 4-meter telescope located inside the premises of Aryabhatta Research Institute of Observational Sciences (ARIES) in the city of Nainital, Uttarakhand, India. It is the first liquid-mirror telescope for astronomy in Asia and currently the largest liquid-mirror telescope in the world after the decommissioning of the Large Zenith Telescope. == History == On 2 June 2022, the telescope saw its first light. On 12 June 2022, it came online. On 21 June 2022, it became ready to observe. On 21 March 2023, it was inaugurated by Jitendra Singh. == Mechanism == The telescope uses elemental mercury as its mirror surface. The mercury is rotated about the axis of the telescope, and due to centrifugal force, takes a parabolic shape to focus incoming light. == See also == Large Zenith Telescope NASA Orbital Debris Observatory == References ==


id: keyhole-problem-20260505-0
file: data/en.wikipedia.org/wiki/Keyhole_problem-0.md
category: reference
title: Keyhole problem
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Keyhole_problem
date_saved: 2026-05-05T09:47:45.084200+00:00
instance: kb-cron
parent: keyhole-problem-20260505-0
summary:
The keyhole problem, in the context of astronomy, refers to the difficulty that azimuth-elevation type telescopes or antenna gimbal systems encounter in crossing the zenith. == Area of visible sky == To track celestial objects as they move across the sky, these systems usually rotate on two axes. Often, a tilting mechanism (elevation) is mounted upon a panning base (azimuth). To cover the complete hemisphere of visible sky, a telescope gimbal can have a 360-degree azimuth range and a 0- to 90-degree elevation range. To visualize this shape, imagine drawing a quarter circle spanning from the horizon to directly above you and revolving it around the vertical axis. If, on the other hand, the gimbal has a range from 0 to slightly less than 90 degrees elevation, the telescope is unable to see a region of sky. == Gimbal behavior == A variation on the keyhole problem involves defining behavior for gimbals with full-circle azimuth range, and at least 90-degree but less than 180-degree elevation range. Imagine a satellite on an orbital path that crosses directly overhead. If the gimbal tilts to track the object from the horizon but must stop at 90 degrees, the entire telescope must pan 180


id: las-cumbres-observatory-20260505-0
file: data/en.wikipedia.org/wiki/Las_Cumbres_Observatory-0.md
category: reference
title: Las Cumbres Observatory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Las_Cumbres_Observatory
date_saved: 2026-05-05T09:47:46.290951+00:00
instance: kb-cron
parent: las-cumbres-observatory-20260505-0
summary:
Las Cumbres Observatory (LCO) is a network of astronomical observatories run by a non-profit private operating foundation directed by the technologist Wayne Rosing. Its offices are in Goleta, California. The telescopes are located at both northern and southern hemisphere sites distributed in longitude around the Earth. For some astronomical objects, the longitudinal spacing of telescopes allows continuous observations over 24 hours or longer. The operating network currently consists of two 2-meter telescopes, nine 1-meter telescopes, and seven 40-centimeter telescopes, placed at six astronomical observatories. The network operates as a single, integrated observing facility, using a software scheduler that continuously optimizes the planned observing schedule of each individual telescope. == History == Rosing incorporated Las Cumbres Observatory in 1993 with the goal of aiding universities, observatories, and individuals in the acquisition and improvement of telescopes, optics, and instrumentation. He also set the objective for the organization to build and implement a global telescope system. In 2005, Rosing established the global telescope version of Las Cumbres Observatory. LCO initially acquired the two Faulkes 2-meter telescopes. Faulkes Telescope North (FTN) located at Haleakala Observatory, on Maui, Hawaii, and Faulkes Telescope South (FTS) at Siding Spring Observatory (SSO), in eastern Australia. LCO also purchased


id: las-cumbres-observatory-20260505-1
file: data/en.wikipedia.org/wiki/Las_Cumbres_Observatory-1.md
category: reference
title: Las Cumbres Observatory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Las_Cumbres_Observatory
date_saved: 2026-05-05T09:47:46.290951+00:00
instance: kb-cron
parent: las-cumbres-observatory-20260505-0
summary:
== Research == The design and operation of the LCO global telescope network provide the unique capabilities required for time domain astronomy. The LCO network offers the ability to observe objects or events continuously and the ability to obtain data rapidly upon the discovery or announcement of an event. The LCO network has been used to study supernovae and other explosive transients; exoplanets, through observations of both transits and microlensing; asteroids; and AGN variability. In 2017 LCO played a critical part in two major discoveries: first visible counterpart of a gravitational wave event, and a new type of supernova with successive explosions. == Education == Since the beginning of LCO, education has been one of its core missions. In 2017, for the first time in LCO's history it issued an open call for education partners, Global Sky Partners—groups who could use their robotic telescopes to inspire diverse audiences with educational and outreach projects that they support. In 2019 there are 20 LCO Global Sky Partners based in the US, Europe, Sub-Saharan Africa, the Middle East, Australia, or running entirely online programs, for students, teachers, and the wider public. In 2019 the reported direct impact of the program was 13,000 individuals


id: liquid-mirror-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Liquid-mirror_telescope-0.md
category: reference
title: Liquid-mirror telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Liquid-mirror_telescope
date_saved: 2026-05-05T09:47:47.467249+00:00
instance: kb-cron
parent: liquid-mirror-telescope-20260505-0
summary:
Liquid-mirror telescopes are telescopes with mirrors made with a reflective liquid. The most common liquid used is mercury, but other liquids will work as well (for example, low-melting point alloys of gallium). The liquid and its container are rotated at a constant speed around a vertical axis, which causes the surface of the liquid to assume a paraboloidal shape. This parabolic reflector can serve as the primary mirror of a reflecting telescope. The rotating liquid assumes the same surface shape regardless of the container's shape; to reduce the amount of liquid metal needed, and thus weight, a rotating mercury mirror uses a container that is as close to the necessary parabolic shape as feasible. Liquid mirrors can be a low-cost alternative to conventional large telescopes. Compared to a solid glass mirror that must be cast, ground, and polished, a rotating liquid-metal mirror is much less expensive to manufacture. Isaac Newton noted that the free surface of a rotating liquid forms a circular paraboloid and can therefore be used as a telescope, but he could not build one because he had no way to stabilize the speed of rotation. The concept was further developed by Ernesto Capocci (1798–1864) of the Naples


id: liquid-mirror-telescope-20260505-1
file: data/en.wikipedia.org/wiki/Liquid-mirror_telescope-1.md
category: reference
title: Liquid-mirror telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Liquid-mirror_telescope
date_saved: 2026-05-05T09:47:47.467249+00:00
instance: kb-cron
parent: liquid-mirror-telescope-20260505-0
summary:
which relates the angular velocity of the rotation of the liquid to the focal length of the paraboloid that is produced by the rotation. Note that no other variables are involved. The density of the liquid, for example, has no effect on the focal length of the paraboloid. The units must be consistent, e.g. f {\displaystyle f} may be in metres, ω {\displaystyle \omega } in radians per second, and g {\displaystyle g} in metres per second-squared. If we write F {\displaystyle F} for the numerical value of the focal length in metres, and S {\displaystyle S} for the numerical value of the rotation speed in revolutions per minute (RPM), then on the Earth's surface, where g {\displaystyle g} is approximately 9.81 metres per second-squared, the last equation reduces to the approximation F S 2 ≈ 447. {\displaystyle FS^{2}\approx 447.} If the focal length is in feet instead of metres, this approximation becomes F S 2 ≈ 1467. {\displaystyle FS^{2}\approx 1467.} The rotation speed is still in RPM. == Liquid-mirror telescopes == === Conventional land-based liquid-mirror telescopes === These are made of liquid stored in a cylindrical container made of a composite material, such as Kevlar. The cylinder is spun


id: liquid-mirror-telescope-20260505-2
file: data/en.wikipedia.org/wiki/Liquid-mirror_telescope-2.md
category: reference
title: Liquid-mirror telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Liquid-mirror_telescope
date_saved: 2026-05-05T09:47:47.467249+00:00
instance: kb-cron
parent: liquid-mirror-telescope-20260505-0
summary:
Usually, the mirror of a liquid-mirror telescope is rotated around two axes simultaneously. For example, the mirror of a telescope on the surface of the Earth rotates at a speed of a few revolutions per minute about a vertical axis to maintain its parabolic shape, and also at a speed of one revolution per day about the Earth's axis because of the rotation of the Earth. Usually (except if the telescope is located at one of the Earth's poles), the two rotations interact so that, in a frame of reference that is stationary relative to the local surface of the Earth, the mirror experiences a torque about an axis that is perpendicular to both rotation axes, i.e. a horizontal axis aligned east–west. Since the mirror is liquid, it responds to this torque by changing its aim direction. The point in the sky at which the mirror is aimed is not exactly overhead, but is displaced slightly to the north or south. The amount of the displacement depends on the latitude, the rotation speeds, and the parameters of the telescope's design. On the Earth, the displacement is small, typically a few arcseconds, which can, nevertheless, be significant in astronomical observations. If


id: list-of-original-copies-of-the-porter-garden-telescope-20260505-0
file: data/en.wikipedia.org/wiki/List_of_original_copies_of_the_Porter_Garden_Telescope-0.md
category: reference
title: List of original copies of the Porter Garden Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_original_copies_of_the_Porter_Garden_Telescope
date_saved: 2026-05-05T09:47:48.653586+00:00
instance: kb-cron
parent: list-of-original-copies-of-the-porter-garden-telescope-20260505-0
summary:
This is a list of the known original copies of The Porter Garden Telescope. For information purposes, are also included those copies that their location are currently unknown, but there are records with some of their data. == See also == The Porter Garden Telescope == References ==


id: maunakea-spectroscopic-explorer-20260505-0
file: data/en.wikipedia.org/wiki/Maunakea_Spectroscopic_Explorer-0.md
category: reference
title: Maunakea Spectroscopic Explorer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Maunakea_Spectroscopic_Explorer
date_saved: 2026-05-05T09:47:49.872045+00:00
instance: kb-cron
parent: maunakea-spectroscopic-explorer-20260505-0
summary:
The Maunakea Spectroscopic Explorer (MSE) is a collaborative project to revitalize the Canada–France–Hawaii Telescope (CFHT). The group aims to replace the 1970s optical telescope with a modern segmented-mirror telescope and dedicated science instrumentation, while reusing the existing Maunakea summit building and facility. MSE will use an 11.25 meter aperture telescope and dedicated multiobject fibre spectroscopy instrumentation to perform survey science observations, collecting spectra from more than 4,000 astronomical targets simultaneously. The project completed a conceptual design in early 2018. However, the 2022 Maunakea moratorium on new leases for telescopes delays decision-making on MSE until after 2030; as of late 2024 the CFHT Board has curtailed funding of any MSE activities for the time being . == Background == === Partnership and funding === The MSE project initially took shape through a feasibility study led by the National Research Council of Canada, which showed the strength of the science case for a large aperture dedicated multiobject spectroscopic facility, as well as the technical feasibility of such a facility as an upgrade to CFHT. In 2014, the CFHT established a project office in Waimea HI, to lead and develop the project through to the start of construction. The MSE participants in 2018


id: maunakea-spectroscopic-explorer-20260505-1
file: data/en.wikipedia.org/wiki/Maunakea_Spectroscopic_Explorer-1.md
category: reference
title: Maunakea Spectroscopic Explorer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Maunakea_Spectroscopic_Explorer
date_saved: 2026-05-05T09:47:49.872045+00:00
instance: kb-cron
parent: maunakea-spectroscopic-explorer-20260505-0
summary:
==== 4. Examining the connection between galaxies and the large scale structure of the Universe ==== MSE will measure how galaxies evolve and grow relative to the dark matter structure in which they are embedded. This is done through mapping the distribution of stellar populations and supermassive black holes to the dark matter haloes and filamentary structures that dominate the mass density of the Universe, and doing so over all mass and spatial scales. MSE will provide a breakthrough in extragalactic astronomy by linking the formation and evolution of galaxies to the surrounding large-scale structure, across the full range of relevant spatial scales (from kiloparsecs to megaparsecs). ==== 5. Following time-variable events ==== MSE will perform spectroscopic follow-up of time-variable events discovered by LSST, SKA and other all-sky transient surveys. With its large multiplex advantage and good sky overlap with other surveys, MSE can provide large-aperture followup of faint transient events using a few fibres while simultaneously continuing uninterrupted observation of main survey programs with the remainder of the installed fibre set. ==== 6. The growth of supermassive black holes ==== MSE will undertake an extragalactic time domain program to measure directly the accretion rates and masses of a large


id: maunakea-spectroscopic-explorer-20260505-2
file: data/en.wikipedia.org/wiki/Maunakea_Spectroscopic_Explorer-2.md
category: reference
title: Maunakea Spectroscopic Explorer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Maunakea_Spectroscopic_Explorer
date_saved: 2026-05-05T09:47:49.872045+00:00
instance: kb-cron
parent: maunakea-spectroscopic-explorer-20260505-0
summary:
=== Science instrumentation === Science data can be acquired in two possible spectral resolution modes: a high resolution of about R = 20,000 | 40,000, and a low/moderate resolution mode spanning R = 2,000 to R = 6,000. MSE is designed to be able to take spectra in both modes simultaneously during any observation. A fibre optic transmission system relays light gathered into the fibre tips at the telescope optical focal plane, to two banks of spectrometers that will measure the spectrum of the light gathered by each fibre. The fibre tips are positioned precisely at the position of astronomical interest in the focal plane by the array of remotely commandable tilting spine fibre positioners, each responsible for one fibre delivering light to one of the two spectrometer banks. The fibre transmission system uses high numeric aperture fibres to optically directly match the telescope focal ratio, and to provide good mechanical stability and optical throughput while minimizing focal-ratio degradation. The fibre core diameter, which sets the size of the sky sampled by each fibre tip, is different in those fibres used in the high resolution mode from those used in the low/moderate resolution mode, due to the difference in angular


id: meridian-circle-20260505-0
file: data/en.wikipedia.org/wiki/Meridian_circle-0.md
category: reference
title: Meridian circle
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Meridian_circle
date_saved: 2026-05-05T09:47:51.054683+00:00
instance: kb-cron
parent: meridian-circle-20260505-0
summary:
The meridian circle is an instrument for timing of the passage of stars across the local meridian, an event known as a culmination, while at the same time measuring their angular distance from the nadir. These are special purpose telescopes mounted so as to allow pointing only in the meridian, the great circle through the north point of the horizon, the north celestial pole, the zenith, the south point of the horizon, the south celestial pole, and the nadir. Meridian telescopes rely on the rotation of the sky to bring objects into their field of view and are mounted on a fixed, horizontal, east–west axis. The similar transit instrument, transit circle, or transit telescope is likewise mounted on a horizontal axis, but the axis need not be fixed in the east–west direction. For instance, a surveyor's theodolite can function as a transit instrument if its telescope is capable of a full revolution about the horizontal axis. Meridian circles are often called by these names, although they are less specific. For many years, transit timings were the most accurate method of measuring the positions of heavenly bodies, and meridian instruments were relied upon to perform this painstaking work. Before spectroscopy, photography,


id: meridian-circle-20260505-1
file: data/en.wikipedia.org/wiki/Meridian_circle-1.md
category: reference
title: Meridian circle
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Meridian_circle
date_saved: 2026-05-05T09:47:51.054683+00:00
instance: kb-cron
parent: meridian-circle-20260505-0
summary:
Near each end of the axis, attached to the axis and turning with it, was a circle or wheel for measuring the angle of the telescope to the zenith or horizon. Generally of 1 to 3 feet or more in diameter, it was divided to 2 or 5 arcminutes, on a slip of silver set into the face of the circle near the circumference. These graduations were read by microscopes, generally four for each circle, mounted to the piers or a framework surrounding the axis, at 90° intervals around the circles. By averaging the four readings the eccentricity (from inaccurate centering of the circles) and the errors of graduation were greatly reduced. Each microscope was furnished with a micrometer screw, which moved crosshairs, with which the distance of the circle graduations from the centre of the field of view could be measured. The drum of the screw was divided to measure single seconds of arc (0.1" being estimated), while the number of revolutions were counted by a comb like scale in the field of view. The microscopes were given such magnification and placed at such a distance from the circle that one revolution of the micrometer screw corresponded to 1


id: meridian-circle-20260505-2
file: data/en.wikipedia.org/wiki/Meridian_circle-2.md
category: reference
title: Meridian circle
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Meridian_circle
date_saved: 2026-05-05T09:47:51.054683+00:00
instance: kb-cron
parent: meridian-circle-20260505-0
summary:
=== Operation === At the focal plane, the eye end of the telescope had a number of vertical and one or two horizontal wires (crosshairs). In observing stars, the telescope was first directed downward at a basin of mercury forming a perfectly horizontal mirror and reflecting an image of the crosshairs back up the telescope tube. The crosshairs were adjusted until coincident with their reflection, and the line of sight was then perfectly vertical; in this position the circles were read for the nadir point. The telescope was next brought up to the approximate declination of the target star by watching the finder circle. The instrument was provided with a clamping apparatus, by which the observer, after having set the approximate declination, could clamp the axis so the telescope could not be moved in declination, except very slowly by a fine screw. By this slow motion, the telescope was adjusted until the star moved along the horizontal wire (or if there were two, in the middle between them), from the east side of the field of view to the west. Following this, the circles were read by the microscopes for a measurement of the apparent altitude of the star. The


id: meridian-circle-20260505-3
file: data/en.wikipedia.org/wiki/Meridian_circle-3.md
category: reference
title: Meridian circle
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Meridian_circle
date_saved: 2026-05-05T09:47:51.054683+00:00
instance: kb-cron
parent: meridian-circle-20260505-0
summary:
Meridian circles required precise adjustment to do accurate work. The rotation axis of the main telescope needed to be exactly horizontal. A sensitive spirit level, designed to rest on the pivots of the axis, performed this function. By adjusting one of the V-shaped bearings, the bubble was centered. The line of sight of the telescope needed to be exactly perpendicular to the axis of rotation. This could be done by sighting a distant, stationary object, lifting and reversing the telescope on its bearings, and again sighting the object. If the crosshairs did not intersect the object, the line of sight was halfway between the new position of the crosshairs and the distant object; the crosshairs were adjusted accordingly and the process repeated as necessary. Also, if the rotation axis was known to be perfectly horizontal, the telescope could be directed downward at a basin of mercury, and the crosshairs illuminated. The mercury acted as a perfectly horizontal mirror, reflecting an image of the crosshairs back up the telescope tube. The crosshairs could then be adjusted until coincident with their reflection, and the line of sight was then perpendicular to the axis. The line of sight of the telescope needed to


id: meridian-circle-20260505-4
file: data/en.wikipedia.org/wiki/Meridian_circle-4.md
category: reference
title: Meridian circle
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Meridian_circle
date_saved: 2026-05-05T09:47:51.054683+00:00
instance: kb-cron
parent: meridian-circle-20260505-0
summary:
The making of circles was shortly afterwards taken up by Edward Troughton, who constructed the first modern transit circle in 1806 for Groombridge's observatory at Blackheath, the Groombridge Transit Circle (a meridian transit circle). Troughton afterwards abandoned the idea and designed the mural circle to take the place of the mural quadrant. In the United Kingdom, the transit instrument and mural circle continued until the middle of the 19th century to be the principal instrument in observatories, the first transit circle constructed there being that at Greenwich (mounted in 1850). However, on the continent, the transit circle superseded them from the years 1818–1819, when two circles by Johann Georg Repsold and Georg Friedrich von Reichenbach were mounted at Göttingen, and one by Reichenbach at Königsberg. The firm of Repsold and Sons was for a number of years eclipsed by that of Pistor and Martins in Berlin, who furnished various observatories with first-class instruments. Following the death of Martins, the Repsolds again took the lead and made many transit circles. The observatories of Harvard College, Cambridge University and Edinburgh University had large circles by Troughton and Simms. The Airy Transit Circles at the Royal Greenwich Observatory (1851) and that at the


id: multi-conjugate-adaptive-optics-demonstrator-20260505-0
file: data/en.wikipedia.org/wiki/Multi-conjugate_Adaptive_optics_Demonstrator-0.md
category: reference
title: Multi-conjugate Adaptive optics Demonstrator
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Multi-conjugate_Adaptive_optics_Demonstrator
date_saved: 2026-05-05T09:47:52.225578+00:00
instance: kb-cron
parent: multi-conjugate-adaptive-optics-demonstrator-20260505-0
summary:
Multi-conjugate Adaptive optics Demonstrator (MAD) is an instrument that allowed the European Southern Observatory's Very Large Telescope to observe celestial objects with most of the atmosphere's blurring removed. As with other adaptive optics systems, it works by performing real-time corrections to the atmospheric turbulence by means of computer-controlled deformable mirrors. Its particularity is the correction over a wider field of view than previous systems, which only used a single deformable mirror. == References ==


id: multicolor-active-galactic-nuclei-monitoring-20260505-0
file: data/en.wikipedia.org/wiki/Multicolor_Active_Galactic_Nuclei_Monitoring-0.md
category: reference
title: Multicolor Active Galactic Nuclei Monitoring
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Multicolor_Active_Galactic_Nuclei_Monitoring
date_saved: 2026-05-05T09:47:53.404772+00:00
instance: kb-cron
parent: multicolor-active-galactic-nuclei-monitoring-20260505-0
summary:
Multicolor Active Galactic Nuclei Monitoring or MAGNUM was a project completed in 2008, that used a 2 meter (78.7 inch) telescope at Haleakala, Hawaii. The project started in 1995, and with telescope observations starting in 2000 for the scientific study of active galactic nuclei. It was run by the University of Tokyo, the National Astronomical Observatory of Japan, and Australian National University. MAGNUM was one of the telescopes that observed a cosmic explosion billions of years away in 2005. The telescope was used for a long-term study of the size of the universe; for example it studied the Seyfert 1 galaxies NGC 5548, NGC 4051, NGC 3227, and NGC 7469 The telescope was located at the Haleakala Observatory and was installed in north dome previously used by LURE. This was an astronomy project that used an automated telescope to look for AGN at visible and near infrared wavelengths. == References ==


id: narrabri-stellar-intensity-interferometer-20260505-0
file: data/en.wikipedia.org/wiki/Narrabri_Stellar_Intensity_Interferometer-0.md
category: reference
title: Narrabri Stellar Intensity Interferometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Narrabri_Stellar_Intensity_Interferometer
date_saved: 2026-05-05T09:47:54.566878+00:00
instance: kb-cron
parent: narrabri-stellar-intensity-interferometer-20260505-0
summary:
The Narrabri Stellar Intensity Interferometer (NSII) was the first astronomical instrument to measure the diameters of a large number of stars at visible wavelengths. It was designed by (amongst others) Robert Hanbury Brown, who received the Hughes Medal in 1971 for this work. It was built by University of Sydney School of Physics and was located near the town of Narrabri in north-central New South Wales, Australia. Many of the components were constructed in the UK. The design was based on an earlier optical intensity interferometer built by Hanbury Brown and Richard Q. Twiss at Jodrell Bank in the UK. Whilst the original device had a maximum baseline of 10m, the NSII device consisted of a large circular track that allowed the detectors to be separated from 10 to 188m. The NSII operated from 1963 until 1974, and was used to measure the angular diameters of 32 stars. == See also == Lists of telescopes == References == == External links == The angular diameters of 32 stars, Mon. Not. R. Astron. Soc. Volume 167 pp 121–136 (1974) Hanbury Brown R, The intensity interferometer – its application to astronomy, Taylor & Francis, 1974


id: next-generation-transit-survey-20260505-0
file: data/en.wikipedia.org/wiki/Next-Generation_Transit_Survey-0.md
category: reference
title: Next-Generation Transit Survey
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Next-Generation_Transit_Survey
date_saved: 2026-05-05T09:47:55.779523+00:00
instance: kb-cron
parent: next-generation-transit-survey-20260505-0
summary:
The Next-Generation Transit Survey (NGTS) is a ground-based robotic search for exoplanets. The facility is located at Paranal Observatory in the Atacama Desert in northern Chile, about 2 km from ESO's Very Large Telescope and 0.5 km from the VISTA Survey Telescope. Science operations began in early 2015. The astronomical survey is managed by a consortium of seven European universities and other academic institutions from Chile, Germany, Switzerland, and the United Kingdom. Prototypes of the array were tested in 2009 and 2010 on La Palma, and from 2012 to 2014 at Geneva Observatory. The aim of NGTS is to discover super-Earths and exo-Neptunes transiting relatively bright and nearby stars with an apparent magnitude of up to 13. The survey uses transit photometry, which precisely measures the dimming of a star to detect the presence of a planet when it crosses in front of it. NGTS consists of an array of twelve commercial 0.2-metre telescopes (f/2.8), each equipped with a red-sensitive CCD camera operating in the visible and near-infrared at 600–900 nm. The array covers an instantaneous field of view of 96 square degrees (8 deg2 per telescope) or around 0.23% of the entire sky. NGTS builds heavily on experience with


id: next-generation-transit-survey-20260505-1
file: data/en.wikipedia.org/wiki/Next-Generation_Transit_Survey-1.md
category: reference
title: Next-Generation Transit Survey
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Next-Generation_Transit_Survey
date_saved: 2026-05-05T09:47:55.779523+00:00
instance: kb-cron
parent: next-generation-transit-survey-20260505-0
summary:
== Partnership == Although located at Paranal Observatory, NGTS is not in fact operated by ESO, but by a consortium of seven academic institutions from Chile, Germany, Switzerland, and the United Kingdom: DLR, Institute for Planetary Research Geneva Observatory Queen's University Belfast University of Cambridge University of Chile University of Leicester University of Warwick == Results == On 31 October 2017, the discovery of NGTS-1b, a confirmed hot Jupiter-sized extrasolar planet orbiting NGTS-1, an M-dwarf star, about half the mass and radius of the Sun, every 2.65 days, was reported by the survey team. Daniel Bayliss, of the University of Warwick, and lead author of the study describing the discovery of NGTS-1b, stated, "The discovery of NGTS-1b was a complete surprise to us—such massive planets were not thought to exist around such small stars – importantly, our challenge now is to find out how common these types of planets are in the Galaxy, and with the new Next-Generation Transit Survey facility we are well-placed to do just that." On 3 September 2018, the discovery of NGTS-4b, a sub-Neptune-sized planet transiting a 13th magnitude K-dwarf in a 1.34 day orbit. NGTS-4b has a mass 20.6 ± 3.0 M🜨 and radius 3.18


id: non-achromatic-objective-20260505-0
file: data/en.wikipedia.org/wiki/Non-achromatic_objective-0.md
category: reference
title: Non-achromatic objective
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Non-achromatic_objective
date_saved: 2026-05-05T09:47:56.934685+00:00
instance: kb-cron
parent: non-achromatic-objective-20260505-0
summary:
A non-achromatic objective is an objective lens which is not corrected for chromatic aberration. In telescopes they can a be pre-18th century simple single element objective lenses which were used before the invention of doublet achromatic lenses. They can also be specialty monochromatic lenses used in modern research telescopes and other instruments. == Non-achromatic telescope objectives == === Early non-achromatic objectives === Early telescope objective, such as those built by Johannes Hevelius and Christiaan Huygens and his brother Constantijn Huygens, Jr., utilized single small (2"-8") positive lenses with enormous focal lengths (up to 150 feet in length in tube telescopes and up to 600 feet in non-tube aerial telescopes). This allowed the observer to use higher magnification while limiting the interfering rainbow halos caused by chromatic aberration (the uncorrected chromatic aberration fell within the large diffraction pattern at focus). === Modern non-achromatic objectives === Modern instruments may use a non-achromatic objective lens which is well-corrected for spherical aberration and off-axis aberrations such as coma and astigmatism over the desired field of view at only one wavelength. Monochromatically corrected objectives can be found in solar telescopes working with narrow spectral lines such as the hydrogen alpha spectral line of 0.6562725 micrometres.


id: nuclear-compton-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Nuclear_Compton_Telescope-0.md
category: reference
title: Nuclear Compton Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Nuclear_Compton_Telescope
date_saved: 2026-05-05T09:47:58.140551+00:00
instance: kb-cron
parent: nuclear-compton-telescope-20260505-0
summary:
The Nuclear Compton Telescope (NCT) is a balloon-borne Compton telescope to observe the gamma-ray sky in the energy range from a few hundred keV to several MeV. Its main goals are to improve the understanding of Galactic nucleosynthesis, gamma-ray bursts, supernovae, black holes, and more. == Instrumentation == The Compton telescope uses an array of twelve germanium detectors with high spectral resolution to detect gamma rays. On its bottom half the detector is surrounded by a bismuth germanate scintillator to shield it from atmospheric gamma rays. The telescope has an overall field of view (FOV) of 25% of the sky. == Flights == Since low-to-medium-energy gamma rays are only detectable from above the atmosphere, NCT is launched with a large 1-million m3 (35-million ft3) Helium balloon into the stratosphere. So far NCT had two successful and one unsuccessful balloon campaigns: A two-detector prototype was successfully test flown on 1 June 2005 from the Scientific Balloon Flight Facility, Fort Sumner, New Mexico. On 19 May 2009, the full instrument successfully launched from Fort Sumner in New Mexico and was able to observe the Crab Pulsar. Unfortunately, on 28 April 2010 a launch mishap occurred at Alice Springs, Australia, when the gondola


id: ohana-project-20260505-0
file: data/en.wikipedia.org/wiki/Ohana_project-0.md
category: reference
title: Ohana project
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ohana_project
date_saved: 2026-05-05T09:47:59.306726+00:00
instance: kb-cron
parent: ohana-project-20260505-0
summary:
The Ohana project aims to use seven big telescopes on top of Mauna Kea, Hawaiʻi Big Island, in an interferometer configuration. Mauna Kea is a former volcano whose height is 13,600 ft (4,145 m). It is a good site for telescopes which probe the universe in the optical and infrared wavelengths because of its altitude and low levels of light pollution. OHANA stands for Optical Hawaiian Array for Nanoradian Astronomy. In Hawaiʻian, ‘ohana means "family". == Telescopes involved in the project == Among the telescopes belonging to the Mauna Kea Observatory, seven are involved in the ‘OHANA project : Two Keck telescopes which each have a 10 m diameter primary mirror. Subaru with an 8.2 m primary mirror. Gemini North with an 8 m primary mirror. Canada France Hawaii Telescope (CFHT) with a prime focus/Cassegrain configuration with a usable aperture diameter of 3.58 meters. The Infrared Telescope Facility is a 3 m telescope. The United Kingdom Infrared Telescope is a 3.8 m telescope. == Stages of the project == The project's big improvement is the use of optic fiber instead of mirrors to guide the beams in the interferometer recombination system. Before doing some tests with the telescopes, scientists had


id: optical-gravitational-lensing-experiment-20260505-0
file: data/en.wikipedia.org/wiki/Optical_Gravitational_Lensing_Experiment-0.md
category: reference
title: Optical Gravitational Lensing Experiment
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Optical_Gravitational_Lensing_Experiment
date_saved: 2026-05-05T09:48:00.497173+00:00
instance: kb-cron
parent: optical-gravitational-lensing-experiment-20260505-0
summary:
The Optical Gravitational Lensing Experiment (OGLE) is a Polish astronomical project based at the University of Warsaw that runs a long-term variability sky survey (1992–present). The main goals are the detection and classification of variable stars (pulsating and eclipsing), discovery of microlensing events, dwarf novae, and studies of the structure of the Galaxy and the Magellanic Clouds. Since the project began in 1992, it has discovered a multitude of extrasolar planets, together with the first planet discovered using the transit method (OGLE-TR-56b) and gravitational microlensing. The project has been led by professor Andrzej Udalski since its inception. == Description == The main targets of the experiment are the Magellanic Clouds and the Galactic Bulge, because of the large number of intervening stars that can be used for microlensing during a stellar transit. Most of the observations have been made at the Las Campanas Observatory in Chile. Cooperating institutions include Princeton University and the Carnegie Institution. The project is now in its fourth phase. The first phase, OGLE-I (1992–1995), used the 1.0-metre (3 ft 3 in) Swope telescope and a single-chip CCD sensor. For OGLE-II (1996–2000), a 1.3-metre (4 ft 3 in) telescope dedicated to the project (the Warsaw telescope) was


id: optical-system-for-imaging-and-low-resolution-integrated-spectroscopy-20260505-0
category: reference
title: Optical System for Imaging and low Resolution Integrated Spectroscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Optical_System_for_Imaging_and_low_Resolution_Integrated_Spectroscopy
date_saved: 2026-05-05T09:48:01.650993+00:00
instance: kb-cron
parent: optical-system-for-imaging-and-low-resolution-integrated-spectroscopy-20260505-0
file:
data/en.wikipedia.org/wiki/Optical_System_for_Imaging_and_low_Resolution_Integrated_Spectroscopy-0.md

summary:
The Optical System for Imaging and low Resolution Integrated Spectroscopy (OSIRIS) is an optical spectrometer at the Gran Telescopio Canarias (GTC) in Spain. It was the first instrument in operation at the GTC. OSIRIS's key scientific project is OTELO. Sensitive in the wavelength range from 365 through 1000 nm, OSIRIS is a multiple purpose instrument for imaging and low-resolution long slit and multiple object spectroscopy (MOS). Imaging can be done using broad-band filters or narrow-band tunable filters with FWHM ranging from 0.2 to 0.9 nm at 365 nm, through 0.9 to 1.2 at 1000 nm. OSIRIS observing modes include also fast photometry and spectroscopy. OSIRIS's field of view is of 8.5×8.5 arcminutes and the maximum nominal spectral resolution is of 5000 for a slit width of 0.6 arcsec. MOS incorporates detector charge shuffling co-ordinated with telescope nodding for an excellent sky subtraction. The use of tunable filters is a completely new feature in 8 to 10 m class telescopes that will allow observing the very faint and distant emission line objects. == External links == Gran Telescopio CANARIAS OSIRIS instrument page OSIRIS Home Page (IAC)


id: optical-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Optical_telescope-0.md
category: reference
title: Optical telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Optical_telescope
date_saved: 2026-05-05T09:48:03.007847+00:00
instance: kb-cron
parent: optical-telescope-20260505-0
summary:
An optical telescope gathers and focuses light mainly from the visible part of the electromagnetic spectrum, to create a magnified image for direct visual inspection, to make a photograph, or to collect data through electronic image sensors. There are three primary types of optical telescope : Refracting telescopes, which use lenses and less commonly also prisms (dioptrics) Reflecting telescopes, which use mirrors (catoptrics) Catadioptric telescopes, which combine lenses and mirrors An optical telescope's ability to resolve small details is directly related to the diameter (or aperture) of its objective (the primary lens or mirror that collects and focuses the light), and its light-gathering power is related to the area of the objective. The larger the objective, the more light the telescope collects and the finer detail it resolves. People use optical telescopes (including monoculars and binoculars) for outdoor activities such as observational astronomy, ornithology, pilotage, hunting and reconnaissance, as well as indoor/semi-outdoor activities such as watching performance arts and spectator sports. == History == The telescope is more a discovery of optical craftsmen than an invention of a scientist. The lens and the properties of refracting and reflecting light had been known since antiquity, and theory on how they worked


id: optical-telescope-20260505-1
file: data/en.wikipedia.org/wiki/Optical_telescope-1.md
category: reference
title: Optical telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Optical_telescope
date_saved: 2026-05-05T09:48:03.007847+00:00
instance: kb-cron
parent: optical-telescope-20260505-0
summary:
Most telescope designs produce an inverted image at the focal plane; these are referred to as inverting telescopes. In fact, the image is both turned upside down and reversed left to right, so that altogether it is rotated by 180 degrees from the object orientation. In astronomical telescopes the rotated view is normally not corrected, since it does not affect how the telescope is used. However, a mirror diagonal is often used to place the eyepiece in a more convenient viewing location, and in that case the image is erect, but still reversed left to right. In terrestrial telescopes such as spotting scopes, monoculars and binoculars, prisms (e.g., Porro prisms) or a relay lens between objective and eyepiece are used to correct the image orientation. There are telescope designs that do not present an inverted image such as the Galilean refractor and the Gregorian reflector. These are referred to as erecting telescopes. === Design variants === Many types of telescope fold or divert the optical path with secondary or tertiary mirrors. These may be integral part of the optical design (Newtonian telescope, Cassegrain reflector or similar types), or may simply be used to place the eyepiece or detector at a


id: optical-telescope-20260505-2
file: data/en.wikipedia.org/wiki/Optical_telescope-2.md
category: reference
title: Optical telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Optical_telescope
date_saved: 2026-05-05T09:48:03.007847+00:00
instance: kb-cron
parent: optical-telescope-20260505-0
summary:
=== Focal length and focal ratio === The focal length of an optical system is a measure of how strongly the system converges or diverges light. For an optical system in air, it is the distance over which initially collimated rays are brought to a focus. A system with a shorter focal length has greater optical power than one with a long focal length; that is, it bends the rays more strongly, bringing them to a focus in a shorter distance. In astronomy, the f-number is commonly referred to as the focal ratio notated as N {\displaystyle N} . The focal ratio of a telescope is defined as the focal length f {\displaystyle f} of an objective divided by its diameter D {\displaystyle D} or by the diameter of an aperture stop in the system. The focal length controls the field of view of the instrument and the scale of the image that is presented at the focal plane to an eyepiece, film plate, or CCD. An example of a telescope with a focal length of 1200 mm and aperture diameter of 254 mm is given by: N = f D = 1200 254 ≈ 4.7 {\displaystyle N={\frac {f}{D}}={\frac {1200}{254}}\approx


id: optical-telescope-20260505-3
file: data/en.wikipedia.org/wiki/Optical_telescope-3.md
category: reference
title: Optical telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Optical_telescope
date_saved: 2026-05-05T09:48:03.007847+00:00
instance: kb-cron
parent: optical-telescope-20260505-0
summary:
==== Visual ==== The visual magnification M {\displaystyle M} of the field of view through a telescope can be determined by the telescope's focal length f {\displaystyle f} divided by the eyepiece focal length f e {\displaystyle f_{e}} (or diameter). The maximum is limited by the focal length of the eyepiece. An example of visual magnification using a telescope with a 1200 mm focal length and 3 mm eyepiece is given by: M = f f e = 1200 3 = 400 {\displaystyle M={\frac {f}{f_{e}}}={\frac {1200}{3}}=400} ==== Minimum ==== There are two issues constraining the lowest useful magnification on a telescope: The light beam exiting the eyepiece needs to be small enough to enter the pupil of the observer's eye. If the cylinder of light emerging from they eyepiece is too wide to enter the observer's eye, some of the light gathered by the telescope will be wasted, and the image seen will be dimmer and less clear than it would be at a higher magnification. For telescope designs with obstructions in the light path (e.g. most catadioptric telescopes, but not spyglass-style refracting telescopes) the magnification must be high enough to keep the central obstruction out of focus, to prevent


id: optical-telescope-20260505-4
file: data/en.wikipedia.org/wiki/Optical_telescope-4.md
category: reference
title: Optical telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Optical_telescope
date_saved: 2026-05-05T09:48:03.007847+00:00
instance: kb-cron
parent: optical-telescope-20260505-0
summary:
Decreasing the magnification past this limit will not increase brightness nor improve clarity: Beyond this limit there is no benefit from lower magnification. Likewise calculating the exit pupil d e p {\displaystyle \ d_{\mathsf {ep}}\ } is a division of the aperture diameter D {\displaystyle \ D\ } and the visual magnification M {\displaystyle \ M\ } used. The minimum often may not be reachable with some telescopes, a telescope with a very long focal length may require a longer focal length eyepiece than is available. An example of the lowest usable magnification using a fairly common 10″ (254 mm) aperture and the standard adult 7 mm maximum exit pupil is given by: M m i n = D d e p = 254 7 ≈ 36 × . {\displaystyle \ M_{\mathsf {min}}={\frac {D}{\ d_{\mathsf {ep}}}}={\frac {\ 254\ }{7}}\approx 36\!\times ~.} If the telescope happened to have a 1200mm focal length ( L {\displaystyle \ L\ } ), the longest recommended eyepiece focal length ( ℓ {\displaystyle \ \ell \ } ) would be ℓ = L M ≈ 1 200 m m 36 ≈ 33 m m . {\displaystyle \ \ell ={\frac {\ L\ }{M}}\approx {\frac {\ 1\ 200{\mathsf


id: optical-telescope-20260505-5
file: data/en.wikipedia.org/wiki/Optical_telescope-5.md
category: reference
title: Optical telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Optical_telescope
date_saved: 2026-05-05T09:48:03.007847+00:00
instance: kb-cron
parent: optical-telescope-20260505-0
summary:
==== Apparent ==== Apparent field of view (commonly referred to as AFOV) is the perceived angular size of the field stop of the eyepiece, typically measured in degrees. It is a fixed property of the eyepiece's optical design, with common commercially available eyepieces offering a range of apparent fields from 40° to 120°. The apparent field of view of an eyepiece is limited by a combination of the eyepiece's field stop diameter, and focal length, and is independent of magnification used. In an eyepiece with a very wide apparent field of view, the observer may perceive that the view through the telescope stretches out to their peripheral vision, giving a sensation that they are no longer looking through an eyepiece, or that they are closer to the subject of interest than they really are. In contrast, an eyepiece with a narrow apparent field of view may give the sensation of looking through a tunnel or small porthole window, with the black field stop of the eyepiece occupying most of the observer's vision. A wider apparent field of view permits the observer to see more of the subject of interest (that is, a wider true field of view) without reducing magnification


id: optical-telescope-20260505-6
file: data/en.wikipedia.org/wiki/Optical_telescope-6.md
category: reference
title: Optical telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Optical_telescope
date_saved: 2026-05-05T09:48:03.007847+00:00
instance: kb-cron
parent: optical-telescope-20260505-0
summary:
=== Field of view and magnification relationship === Finding what can be seen through the optical system begins with the eyepiece providing the field of view and magnification; the magnification is given by the division of the telescope and eyepiece focal lengths. Using an example of an amateur telescope such as a Newtonian telescope with an aperture D {\displaystyle D} of 130 mm (5") and focal length f {\displaystyle f} of 650 mm (25.5 inches), one uses an eyepiece with a focal length d {\displaystyle d} of 8 mm and apparent FOV v a {\displaystyle v_{a}} of 52°. The magnification at which the observable world is viewed is given by: M = f d = 650 8 = 81.25 {\displaystyle M={\frac {f}{d}}={\frac {650}{8}}=81.25} . The field of view v t {\displaystyle v_{t}} requires the magnification, which is formulated by its division over the apparent field of view: v t = v a M = 52 81.25 = 0.64 {\displaystyle v_{t}={\frac {v_{a}}{M}}={\frac {52}{81.25}}=0.64} . The resulting true field of view is 0.64°, not allowing an object such as the Orion Nebula, which appears elliptical with an angular diameter of 65 × 60 arcminutes, to be viewable through the telescope in its


id: optical-telescope-20260505-7
file: data/en.wikipedia.org/wiki/Optical_telescope-7.md
category: reference
title: Optical telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Optical_telescope
date_saved: 2026-05-05T09:48:03.007847+00:00
instance: kb-cron
parent: optical-telescope-20260505-0
summary:
The derivation of this equation is fairly straightforward and the result is the same for reflecting or refracting telescopes. However, conceptually it is easier to derive by considering a reflecting telescope. If an extended object with angular size α {\displaystyle \alpha } is observed through a telescope, then due to the Laws of reflection and Trigonometry the size of the image projected onto the focal plane will be s = tan ⁡ ( α ) f . {\displaystyle s=\tan(\alpha )f.} The image scale (angular size of object divided by size of projected image) will be i = α s = α tan ⁡ ( α ) f , {\displaystyle i={\frac {\alpha }{s}}={\frac {\alpha }{\tan(\alpha )f}},} and by using the small angle relation tan ⁡ ( a ) ≈ a {\displaystyle \tan(a)\approx a} , when a ≪ 1 {\displaystyle a\ll 1} (N.B. only valid if a {\displaystyle a} is in radians), we obtain i = α α f = 1 f . {\displaystyle i={\frac {\alpha }{\alpha f}}={\frac {1}{f}}.} == Imperfect images == No telescope can form a perfect image. Even if a reflecting telescope could have a perfect mirror, or a refracting telescope could have a perfect lens, the effects of


id: optical-telescope-20260505-8
file: data/en.wikipedia.org/wiki/Optical_telescope-8.md
category: reference
title: Optical telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Optical_telescope
date_saved: 2026-05-05T09:48:03.007847+00:00
instance: kb-cron
parent: optical-telescope-20260505-0
summary:
Relatively cheap, mass-produced ~2 meter telescopes have recently been developed and have made a significant impact on astronomy research. These allow many astronomical targets to be monitored continuously, and for large areas of sky to be surveyed. Many are robotic telescopes, computer controlled over the internet (see e.g. the Liverpool Telescope and the Faulkes Telescope North and South), allowing automated follow-up of astronomical events. Initially the detector used in telescopes was the human eye. Later, the sensitized photographic plate took its place, and the spectrograph was introduced, allowing the gathering of spectral information. After the photographic plate, successive generations of electronic detectors, such as the charge-coupled device (CCDs), have been perfected, each with more sensitivity and resolution, and often with a wider wavelength coverage. Current research telescopes have several instruments to choose from such as: imagers, of different spectral responses spectrographs, useful in different regions of the spectrum polarimeters, that detect light polarization. The phenomenon of optical diffraction sets a limit to the resolution and image quality that a telescope can achieve, which is the effective area of the Airy disc, which limits how close two such discs can be placed. This absolute limit is called the diffraction limit (and


id: otto-struve-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Otto_Struve_Telescope-0.md
category: reference
title: Otto Struve Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Otto_Struve_Telescope
date_saved: 2026-05-05T09:48:04.179582+00:00
instance: kb-cron
parent: otto-struve-telescope-20260505-0
summary:
The Otto Struve Telescope was the first major telescope to be built at McDonald Observatory. Located in the Davis Mountains in West Texas, the Otto Struve Telescope was designed by Warner & Swasey Company and constructed between 1933 and 1939 by the Paterson-Leitch Company. Its 82-inch (2.1 m) mirror was the second largest in the world at the time. It was named after the Ukrainian-American astronomer of Baltic German origin Otto Struve in 1966, three years after his death; Struve had been the director of McDonald Observatory from 1932–1950. The Davis Mountains is an excellent location for astronomical research because of the clear dry air and moderately high elevation. The remote nature of the facility proved to be a significant challenge in transporting such a large mirror. It was a very precarious journey for the Otto Struve Telescope's mirror to this remote part of Texas and up to the top of Mount Locke. The mirror was transported from the local town of Fort Davis up the mountain by Carleton D. Wilson, owner of a local trucking company, while locals cheered as they looked on. The Otto Struve telescope is still in use today. It is updated with modern imaging detectors


id: palomar-testbed-interferometer-20260505-0
file: data/en.wikipedia.org/wiki/Palomar_Testbed_Interferometer-0.md
category: reference
title: Palomar Testbed Interferometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Palomar_Testbed_Interferometer
date_saved: 2026-05-05T09:48:05.305594+00:00
instance: kb-cron
parent: palomar-testbed-interferometer-20260505-0
summary:
The Palomar Testbed Interferometer (PTI) was a near infrared, long-baseline stellar interferometer located at Palomar Observatory in north San Diego County, California, United States. It was built by Caltech and the Jet Propulsion Laboratory and was intended to serve as a testbed for developing interferometric techniques to be used at the Keck Interferometer. It began operations in 1995 and achieved routine operations in 1998, producing more than 50 refereed papers in a variety of scientific journals covering topics from high precision astrometry to stellar masses, stellar diameters and shapes. PTI concluded operations in 2008 and has since been dismantled. PTI was notable for being equipped with a "dual-star" system, making it possible to simultaneously observe pairs of stars; this cancels some of the atmospheric effects of astronomical seeing and makes very high precision measurements possible. A groundbreaking study with the Palomar Testbed Interferometer revealed that the star Altair is not spherical, but is rather flattened at the poles due to its high rate of rotation. == See also == List of astronomical interferometers at visible and infrared wavelengths List of observatories == References == == External links == Palomar Testbed Interferometer (PTI) at NASA Exoplanet Science Institute. Palomar Testbed Interferometer


id: list-of-telescope-parts-and-construction-20260505-0
file: data/en.wikipedia.org/wiki/List_of_telescope_parts_and_construction-0.md
category: reference
title: List of telescope parts and construction
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_telescope_parts_and_construction
date_saved: 2026-05-05T09:48:06.544020+00:00
instance: kb-cron
parent: list-of-telescope-parts-and-construction-20260505-0
summary:
== Hardware == === Accessories === Finderscope Iron sight Reflector (reflex) sight Cheshire collimator: A simple tool to collimate a telescope === Control === Clock drive GoTo === Mechanical construction === Mirror support cell Serrurier truss Silvering === Mounts === Telescope mount - Types include: Altazimuth mount Equatorial mount Equatorial platform Poncet Platform Fork mount German equatorial mount Springfield mount === Optics === Mirrors and lenses are the critical light-bending components of a telescope. Objective: The first lens or curved mirror that collects and focuses the incoming light. Primary lens: The objective of a refracting telescope. Primary mirror: The objective of a reflecting telescope. Corrector plate: A full aperture negative lens placed before a primary mirror designed to correct the optical aberrations of the mirror. Schmidt corrector plate: An aspheric-shaped corrector plate used in the Schmidt telescope. Meniscus corrector: A meniscus-shaped corrector plate usually used in the Maksutov telescope. Focusing mask: A full aperture mask temporarily placed before the primary mirror to aid in focusing the telescope. Bahtinov mask Carey mask Hartmann mask Sub-aperture corrector: One or a series of corrective lens (sometimes combined with a corrective curved mirror) placed after (near the focus) a primary mirror designed to correct


id: periscope-lens-20260505-0
file: data/en.wikipedia.org/wiki/Periscope_lens-0.md
category: reference
title: Periscope lens
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Periscope_lens
date_saved: 2026-05-05T09:48:07.723099+00:00
instance: kb-cron
parent: periscope-lens-20260505-0
summary:
A periscope lens, sometimes called a folded lens, is a mechanical assembly of lens elements that uses a prism or mirror to redirect the light through the lenses with a 90° angle to the optical axis, as in a periscope. == Uses == The Kenworthy/Nettmann Snorkel Camera System, introduced in 1967 by N. Paul Kenworthy and Bob Nettmann, uses periscope lenses to allow filming very small scale models and objects from a very close distance. This system uses a full-size movie camera with downward-extending periscope attachment, which has a length of 24 inches (0.61 m) and a diameter of 2+1⁄2 to 1⁄2 inch (64 to 13 mm). Similar design is used to allow wide-angle lens protruding from aircraft for aerial cinematography. Minolta DiMAGE X introduced in 2002 was among the first digital cameras to use a folded lens; that design was later adopted on other compact digital cameras. Smartphones use periscope lenses to allow larger zoom ratios without increasing their thickness significantly. The increased optical zoom range is aimed to improve macro photography. With a periscope lens, the zoom lenses are turned by 90° and are aligned along the length or the width of the smartphone instead of its depth.


id: plate-optimizer-20260505-0
file: data/en.wikipedia.org/wiki/PLate_OPtimizer-0.md
category: reference
title: PLate OPtimizer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/PLate_OPtimizer
date_saved: 2026-05-05T09:48:09.010806+00:00
instance: kb-cron
parent: plate-optimizer-20260505-0
summary:
PLate OPtimizer, or PLOP is a CAD program used by amateur telescope makers to design primary mirror support cells for reflecting telescopes. It was developed by telescope maker David Lewis, first described in 1999, and used to simplify calculations needed in the design of mirror support cells. It was based on Toshimi Taki's 1993 program PLATE, with a simplified user interface, thus giving it wide acceptance among makers of large Dobsonian style amateur telescopes, with good support of mirrors as thin as two inches for a diameter of thirty inches. == Comparisons and limitations == A basic mirror cell may be built using minimal calculation and simple materials such as wood and outdoor carpet, with a good example being Dobson's original telescopes. However, as amateurs sought to build larger and thinner mirrors, they found such designs inadequate. Many amateur telescope makers use cells which are designed via equal area rule calculation, using programs such as David Chandler's public domain program, Cell. However, such calculation does not account for mechanical stresses introduced in one part of a telescope mirror by another part, whereas finite element analysis can be used to reduce such stress. Although general finite element analysis programs such as


id: polar-alignment-20260505-0
file: data/en.wikipedia.org/wiki/Polar_alignment-0.md
category: reference
title: Polar alignment
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Polar_alignment
date_saved: 2026-05-05T09:48:10.199643+00:00
instance: kb-cron
parent: polar-alignment-20260505-0
summary:
Polar alignment is the act of aligning the rotational axis of a telescope's equatorial mount or a sundial's gnomon with a celestial pole to parallel Earth's axis. == Alignment methods == The method to use differs depending on whether the alignment is taking place in daylight or at night. Furthermore, the method differs if the alignment is done in the Northern Hemisphere or Southern Hemisphere. The purpose of the alignment also must be considered; for example, the value of accuracy is much more significant in astrophotography than in casual stargazing. === Aiming at the pole stars === In the Northern Hemisphere, sighting Polaris the North Star is the usual procedure for aligning a telescope mount's polar axis parallel to the Earth's axis. Polaris is approximately three-quarters of a degree from the North Celestial Pole, and is easily seen by the naked eye. σ Octantis, sometimes known as the South Star, can be sighted in the Southern hemisphere to perform a polar alignment. At magnitude +5.6, it is difficult for inexperienced observers to locate in the sky. Its declination of -88° 57′ 23″ places it 1° 2′ 37" from the South Celestial Pole. An even closer star BQ Octantis of magnitude


id: polar-alignment-20260505-1
file: data/en.wikipedia.org/wiki/Polar_alignment-1.md
category: reference
title: Polar alignment
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Polar_alignment
date_saved: 2026-05-05T09:48:10.199643+00:00
instance: kb-cron
parent: polar-alignment-20260505-0
summary:
Δ α = Δ e ⋅ tan ⁡ δ ⋅ sin ⁡ h + Δ a ⋅ ( sin ⁡ Φ − cos ⁡ Φ ⋅ tan ⁡ δ ⋅ cos ⁡ h ) , Δ δ = Δ e ⋅ cos ⁡ h + Δ a ⋅ cos ⁡ Φ ⋅ sin ⁡ h , {\displaystyle {\begin{aligned}\Delta \alpha &=\Delta e\cdot \tan \delta \cdot \sin h+\Delta a\cdot (\sin \Phi -\cos \Phi \cdot \tan \delta \cdot \cos h),\\\Delta \delta &=\Delta e\cdot \cos h+\Delta a\cdot \cos \Phi \cdot \sin h,\end{aligned}}} where α {\displaystyle \alpha } is right ascension, δ {\displaystyle \delta } is declination, Φ {\displaystyle \Phi } is site latitude, h {\displaystyle h} is the hour angle of the reference point equals ( α {\displaystyle \alpha } − local sidereal time), Δ α {\displaystyle \Delta \alpha } is error in right ascension, Δ δ {\displaystyle \Delta \delta } is error in declination, Δ e {\displaystyle \Delta e} is polar error in elevation (altitude), Δ a {\displaystyle \Delta a} is polar error in azimuth. The inverse can be calculated if the above formula is written in matrix notation. So the polar error expressed in Δe and Δa can be calculated from the


id: purple-crow-lidar-20260505-0
file: data/en.wikipedia.org/wiki/Purple_Crow_Lidar-0.md
category: reference
title: Purple Crow Lidar
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Purple_Crow_Lidar
date_saved: 2026-05-05T09:48:11.428444+00:00
instance: kb-cron
parent: purple-crow-lidar-20260505-0
summary:
The Purple Crow Lidar is a powerful lidar (laser radar) that emits pulses of intensely bright light. The bright light scatters off air molecules, and the reflections are collected by a large telescope. == Telescope == The telescope is formed by rotating liquid mercury at 10 r.p.m. in a 2.65-m diameter container. This liquid mirror technology has been made and developed at Université Laval in Québec City. Such rotating measurement allow air density, pressure, temperature, and composition to be measured. Which can be useful to collect data for global warming and weather prediction. == Weather prediction == This chart is used to determine and predict the weather at Purple Crow Lidar Facility in London Ontario for astronomical observing. == Location == The Purple Crow operates from the Echo Base Observatory located at Western's Environmental Science Field Station located near London, Ontario, Canada. == People in charge == The Purple Crow Lidar research project is headed by Professor Robert J. Sica in the Physics Department at UWO London Ontario. Its main support comes from the Natural Science and Engineering Research Council of Canada (NSERC). == See also == Large Zenith Telescope Liquid-mirror telescope == References ==


id: ronchi-test-20260505-0
file: data/en.wikipedia.org/wiki/Ronchi_test-0.md
category: reference
title: Ronchi test
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ronchi_test
date_saved: 2026-05-05T09:48:12.773082+00:00
instance: kb-cron
parent: ronchi-test-20260505-0
summary:
In optical testing a Ronchi test is a method of determining the surface shape (figure) of a mirror used in telescopes and other optical devices. == Description == In 1923 Italian physicist Vasco Ronchi published a description of the eponymous Ronchi test, which is a variation of the Foucault knife-edge test and which uses simple equipment to test the quality of optics, especially concave mirrors. [1]. A "Ronchi tester" consists of: A light source A diffuser A Ronchi grating A Ronchi grating consists of alternate dark and clear stripes. One design is a small frame with several evenly spaced fine wires attached. Light is emitted through the Ronchi grating (or a single slit), reflected by the mirror being tested, then passes through the Ronchi grating again and is observed by the person doing the test. The observer's eye is placed close to the centre of curvature of the mirror under test looking at the mirror through the grating. The Ronchi grating is a short distance (less than 2 cm) closer to the mirror. The observer sees the mirror covered in a pattern of stripes that reveal the shape of the mirror. The pattern is compared to a mathematically generated diagram


id: rotating-furnace-20260505-0
file: data/en.wikipedia.org/wiki/Rotating_furnace-0.md
category: reference
title: Rotating furnace
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Rotating_furnace
date_saved: 2026-05-05T09:48:14.170841+00:00
instance: kb-cron
parent: rotating-furnace-20260505-0
summary:
A rotating furnace is a device for making solid objects which have concave surfaces that are segments of axially symmetrical paraboloids. Usually, the objects are made of glass. The furnace makes use of the fact, already known to Newton, that the centrifugal-force-induced shape of the top surface of a spinning liquid is a concave paraboloid, identical to the shape of a reflecting telescope's primary focusing mirror. Paraboloids can be used in various ways, including (after being silvered) as primary mirrors in reflecting telescopes and solar cookers. == Design == The furnace includes a mechanism that rotates an open-topped container at constant speed around a vertical axis. A quantity of glass sufficient to make the mirror is placed in the container, heated until it is completely molten, and then allowed to cool while continuing to rotate until it has completely solidified. When the glass is solid, the rotation is stopped and the paraboloidal shape of its top surface is preserved. This process is called spin casting. The same process can be used to make a lens with a concave paraboloidal surface. The other surface is shaped by the container that holds the molten glass acting as a mold. Lenses made this


id: rtt-150-20260505-0
file: data/en.wikipedia.org/wiki/RTT-150-0.md
category: reference
title: RTT-150
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/RTT-150
date_saved: 2026-05-05T09:48:15.458747+00:00
instance: kb-cron
parent: rtt-150-20260505-0
summary:
RTT-150 (Russian: РТТ-150) is a Russian-Turkish 1.5-m optical telescope. It is an international project, jointly led by the Ministry of Education and Science of the Russian Federation and the Council for Technical and Scientific Research of Turkey (TÜBİTAK, TUBITAK). The main performers are Kazan Federal University and the Space Research Institute of the Russian Academy of Sciences from the Russian side and the TUBITAK State Observatory (TUG; observatory code “A84”) from Turkey. Observational time of telescope is shared in the following proportion: 45% - KSU, 15% - IKI RAS (accordance with agreement between parties), and another 40% - are shared between Turkish universities through the TUG. One of the main tasks of the telescope is the optical support of orbital X-ray observatories: INTEGRAL observatory and Spektr-RG. == References == == External links == Official site. TÜBİTAK ULUSAL GÖZLEMEV (Turkey)


id: schiefspiegler-20260505-0
file: data/en.wikipedia.org/wiki/Schiefspiegler-0.md
category: reference
title: Schiefspiegler
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Schiefspiegler
date_saved: 2026-05-05T09:48:16.819579+00:00
instance: kb-cron
parent: schiefspiegler-20260505-0
summary:
The Schiefspiegler (lit. oblique reflector in German), also called tilted-component telescopes (TCT) and off-axis reflecting telescopes, are a type of reflecting telescope featuring an off-axis secondary mirror, and therefore an obstruction-free light path. This is accomplished by tilting the primary mirror so that the secondary mirror does not block incoming light. William Herschel was one of the first to have tilted the mirror of his telescope in order to avoid light loss due to the low reflectivity of his speculum metal mirror. The obstructions in telescope tubes, such as secondary mirrors and their mechanical supports, cut off the intensity of captured light and cause diffraction. The diffraction causes artifacts such as the radial spikes that project from images of bright stars, and it also reduces the contrast of fine details. Schiefspieglers offer a significant increase in contrast, which is useful, for instance, for lunar and planetary study. Tilting the mirrors causes severe coma and astigmatism, however as Anton Kutter showed in the 1950s, by a suitable choice of radii these aberrations can be corrected to an acceptable level. == Implementations == The 1.6 meter New Solar Telescope at the Big Bear Solar Observatory, and the 4 meter Daniel K. Inouye


id: schmidt-v-is-l-camera-20260505-0
file: data/en.wikipedia.org/wiki/Schmidt–Väisälä_camera-0.md
category: reference
title: Schmidt–Väisälä camera
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Schmidt–Väisälä_camera
date_saved: 2026-05-05T09:48:20.279612+00:00
instance: kb-cron
parent: schmidt-v-is-l-camera-20260505-0
summary:
The Schmidt–Väisälä camera is a type of astronomical telescope intended for wide-field (5 to 10 degrees of arc) photographic work. It was designed by Finnish physicist Yrjö Väisälä. == Invention and design == Professor Väisälä originally designed an "astronomical camera" similar to Bernhard Schmidt's Schmidt camera, but the design was unpublished. Väisälä did mention it in a lecture notes in 1924 with a footnote: "problematic spherical focal plane". Once Väisälä saw Schmidt's publication, he promptly went ahead and solved the field-flattening problem in Schmidt's design by placing a doubly convex lens slightly in front of the film holder. This resulting system is known as a Schmidt–Väisälä camera or sometimes as Väisälä camera. This flat-field correction is not perfect, as images suffer from chromatic aberration with different colors ending up at slightly different places. However the approach has attracted interest for modern electronic image sensors with a flat focal plane which cannot be forced into spherical surface shape, nor even manufactured as such. Learning that he lost the inventor status motivated Väisälä to publish his "less than perfect" designs. Professor Väisälä not only designed the new optics, but also built several implementations of the design after Schmidt's publication. His two first


id: secondary-mirror-20260505-0
file: data/en.wikipedia.org/wiki/Secondary_mirror-0.md
category: reference
title: Secondary mirror
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Secondary_mirror
date_saved: 2026-05-05T09:48:21.470642+00:00
instance: kb-cron
parent: secondary-mirror-20260505-0
summary:
A secondary mirror (or secondary) is the second deflecting or focusing mirror element in a reflecting telescope. Light gathered by the primary mirror is directed towards a focal point typically past the location of the secondary. Secondary mirrors in the form of an optically flat diagonal mirror are used to re-direct the light path in designs such as Newtonian reflectors. They are also used to re-direct and extend the light path and modify the final image in designs such as Cassegrain reflectors. The secondary is typically suspended by X-shaped struts (sometimes called a "spider") in the path of light between the source and the primary, but can be mounted on other types of mounts or optical elements such as optical windows, or schmidt and meniscus corrector plates. Employing secondary mirrors in optical systems causes some image distortion due to the obstruction of the secondary itself, and distortion from the spider mounts, commonly seen as cross-shaped diffraction spikes radiating from bright stars seen in astronomical images. For large telescopes, the secondary mirror can reach a significant size. At the Vera C. Rubin Observatory, the secondary for the Simonyi Survey Telescope is nearly four meters in diameter. == See also == List


id: setting-circles-20260505-0
file: data/en.wikipedia.org/wiki/Setting_circles-0.md
category: reference
title: Setting circles
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Setting_circles
date_saved: 2026-05-05T09:48:22.678565+00:00
instance: kb-cron
parent: setting-circles-20260505-0
summary:
Setting circles are used on telescopes equipped with an equatorial mount to find celestial objects by their equatorial coordinates, often used in star charts and ephemerides. == Description == Setting circles consist of two graduated disks attached to the axes – right ascension (RA) and declination (DEC) – of an equatorial mount. The RA disk is graduated into hours, minutes, and seconds. The DEC disk is graduated into degrees, arcminutes, and arcseconds. Since the RA coordinates are fixed onto the celestial sphere, the RA disk is usually driven by a clock mechanism in sync with sidereal time. Locating an object on the celestial sphere using setting circles is similar to finding a location on a terrestrial map using latitude and longitude. Sometimes the RA setting circle has two scales on it: one for the Northern Hemisphere and one for the Southern. == Application == === Research telescopes === Historically setting circles have rivaled the telescopes optics as far as difficulty in construction. Making a set of setting circles required a lot of precision crafting on a dividing engine. Setting circles usually had a large diameter and when combined with a vernier scale could point a telescope to nearly an arc


id: hyeronymus-sirturus-20260505-0
file: data/en.wikipedia.org/wiki/Hyeronymus_Sirturus-0.md
category: reference
title: Hyeronymus Sirturus
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hyeronymus_Sirturus
date_saved: 2026-05-05T09:48:23.925773+00:00
instance: kb-cron
parent: hyeronymus-sirturus-20260505-0
summary:
Hieronymus Sirturus (Geronimo Sirtori (Italian: [ˈsirtori])) was a Milanese scholar who wrote at least two books on politics and telescopes between 1614 and 1618. The Compendium politicum: ex universa civili doctrina Justi Lipsii pro principatu, tum ex Notis integra fide concinnatum was published by Persius in Frankfurt in 1614.., and the Telescopium: sive ars perficiendi novum illud Galilaei virorium instrumentum ad sydera, by Paul Jacob in 1618 His Telescopium book was written around 1612, only 4 years after the telescope was invented. The book contained a complete set of instructions and diagrams for building a refracting telescope. Sirtori pointed out that "a workman had to be most careful in polishing otherwise the lens became lopsided or aspherical with peripheral distortion". The book states that the goal is to create a lens with perfectly spherical surfaces. He may have also invented the method of the spherical grinding of moulds, which improved lens grinding and polishing techniques dramatically. With the rapid dissemination of the telescope the priority question about the inventor soon arose. Sirtori downplayed the achievement of the first discovery of the telescope by presenting the story of Johannes Lippersein, who would have grasped the idea from ‘a genius or some


id: skymapper-20260505-0
file: data/en.wikipedia.org/wiki/SkyMapper-0.md
category: reference
title: SkyMapper
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/SkyMapper
date_saved: 2026-05-05T09:48:25.145232+00:00
instance: kb-cron
parent: skymapper-20260505-0
summary:
SkyMapper is a fully automated 1.35 m (4.4 ft) wide-angle optical telescope at Siding Spring Observatory in northern New South Wales, Australia. It is one of the telescopes of the Research School of Astronomy and Astrophysics of the Australian National University (ANU). The telescope has a compact modified Cassegrain design with a large 0.69 m secondary mirror, which gives it a very wide field of view: its single, dedicated instrument, a 268-million pixel imaging camera, can photograph 5.7 square degrees of sky. The camera has six light filters which span from ultraviolet to near infrared wavelengths. The SkyMapper telescope was built to carry out the Southern Sky Survey, which will image the entire southern sky several times over in SkyMapper's six spectral filters over the course of five years. This survey will be analogous to the Sloan Digital Sky Survey of the Northern hemisphere sky. It has several enhancements, including temporal coverage, more precise measurements of stellar properties and coverage of large parts of the plane of the Galaxy. The telescope and its camera were built by the ANU as a successor to the Great Melbourne Telescope at Mount Stromlo after that telescope was burnt in the 2003 Canberra bushfires.


id: slooh-20260505-0
file: data/en.wikipedia.org/wiki/Slooh-0.md
category: reference
title: Slooh
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Slooh
date_saved: 2026-05-05T09:48:26.404482+00:00
instance: kb-cron
parent: slooh-20260505-0
summary:
Slooh is a robotic telescope service that can be viewed live through a web browser. It was not the first robotic telescope, but it was the first that offered "live" viewing through a telescope via the web. Other online telescopes traditionally email a picture to the recipient. The site has a patent on their live image processing method. Slooh is an online astronomy platform with live-views and telescope rental for a fee. Observations come from a global network of telescopes located in places including Spain and Chile and Siding Spring Australia. The name Slooh comes from the word "slew" to indicate the movement of a telescope, modified with "ooh" to express pleasure and surprise. Slooh, LLC is based in Washington, Connecticut. == History == The service was founded in 2002 by Michael Paolucci. Its Canary Islands telescope went online December 25, 2003, but was not available to the public until 2004. == Participating observatories == The original astronomical observatory is located on the island Tenerife in the Canary Islands on the volcano called Teide. The site is at the 2,300-metre (7,500 ft) elevation and situated away from city light pollution. This (Canary Islands) site includes 2 domes, each with 2


id: space-solar-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Space_Solar_Telescope-0.md
category: reference
title: Space Solar Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Space_Solar_Telescope
date_saved: 2026-05-05T09:48:27.628752+00:00
instance: kb-cron
parent: space-solar-telescope-20260505-0
summary:
The Space Solar Telescope (SST) is a planned Chinese optical space solar telescope. It was first proposed in the 1990s, and is intended to be a 1 metre (3.3 ft) telescope. == See also == List of solar telescopes == References ==


id: spin-casting-mirrors-20260505-0
file: data/en.wikipedia.org/wiki/Spin_casting_(mirrors)-0.md
category: reference
title: Spin casting (mirrors)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Spin_casting_(mirrors)
date_saved: 2026-05-05T09:48:28.829459+00:00
instance: kb-cron
parent: spin-casting-mirrors-20260505-0
summary:
Spin casting is a technique for constructing large parabolic mirrors by using the curved surface formed by a rotating liquid (e.g. in a rotating furnace). It is distinct from the spin casting or centrifugal rubber mold casting (CRMC) technique used for casting metal or plastics. Pioneered by Roger Angel at the Steward Observatory's mirror lab, this makes large (8.4 metres or 28 feet) thin parabolic mirrors by spinning the oven as the glass is melted and cooled. The term is applied to the fabrication of large telescope mirrors, where the natural paraboloid curve followed by the molten glass greatly reduces the amount of grinding required. Rather than being cast by pouring glass into a mold (with top and bottom), an entire turntable containing the peripheral mold, and the back pattern (a honeycomb pattern to lighten the finished product) is contained within a furnace and charged with the glass material used. The assembly (or rotating furnace) is then heated while spun at slow speed until the glass is liquid, then gradually cooled over a period of months. == See also == Rotating furnace – Device for making axially symmetric paraboloids technique Liquid-mirror telescope – Telescope whose mirror is a reflective liquid


id: subaru-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Subaru_Telescope-0.md
category: reference
title: Subaru Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Subaru_Telescope
date_saved: 2026-05-05T09:48:30.022822+00:00
instance: kb-cron
parent: subaru-telescope-20260505-0
summary:
Subaru Telescope (すばる望遠鏡, Subaru Bōenkyō) is the 8.2-metre (320 in) telescope of the National Astronomical Observatory of Japan, located at the Mauna Kea Observatory on Hawaii. It is named after the open star cluster known in English as the Pleiades. It had the largest monolithic primary mirror in the world from its commissioning until the Large Binocular Telescope opened in 2005. == Overview == The Subaru Telescope is a Ritchey-Chretien reflecting telescope. Instruments can be mounted at a Cassegrain focus below the primary mirror; at either of two Nasmyth focal points in enclosures on the sides of the telescope mount, to which light can be directed with a tertiary mirror; or at the prime focus in lieu of a secondary mirror, an arrangement rare on large telescopes, to provide a wide field of view suited to deep wide-field surveys. In 1984, the University of Tokyo formed an engineering working group to develop and study the concept of a 7.5-metre (300 in) telescope. In 1985, the astronomy committee of Japan's science council gave top priority to the development of a "Japan National Large Telescope" (JNLT), and in 1986, the University of Tokyo signed an agreement with the University of Hawaiʻi to


id: subaru-telescope-20260505-1
file: data/en.wikipedia.org/wiki/Subaru_Telescope-1.md
category: reference
title: Subaru Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Subaru_Telescope
date_saved: 2026-05-05T09:48:30.022822+00:00
instance: kb-cron
parent: subaru-telescope-20260505-0
summary:
Hyper Suprime-Cam (HSC) This 900-megapixel ultra-wide-field (1.5° field of view) camera saw first light in 2012, and was offered for open use in 2014. The extremely large wide-field correction optics (a seven-element lens with some elements up to a meter in diameter) was manufactured by Canon and delivered March 29, 2011. It will be used for surveys of weak lensing to determine dark matter distribution. Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument is a high-contrast imaging system for directly imaging exoplanets. The coronagraph uses a Phase Induced Amplitude Apodization (PIAA) design which means it will be able to image planets closer to their stars than conventional Lyot type coronagraph designs. For example, at a distance of 100 pc, the PIAA coronagraph on SCExAO would be able to image from 4 AU outwards while Gemini Planet Imager and VLT-SPHERE from 12 AU outwards. The system also has several other types of coronagraph: Vortex, Four-Quadrant Phase Mask and 8-Octant Phase Mask versions, and a shaped-pupil coronagraph. Phase 1 of construction is complete, and phase 2 construction is expected to be complete by end of 2014 for science operations in 2015. SCExAO will initially use the


id: telescope-mount-20260505-0
file: data/en.wikipedia.org/wiki/Telescope_mount-0.md
category: reference
title: Telescope mount
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Telescope_mount
date_saved: 2026-05-05T09:48:31.212999+00:00
instance: kb-cron
parent: telescope-mount-20260505-0
summary:
A telescope mount is a mechanical structure which supports a telescope. Telescope mounts are designed to support the mass of the telescope and allow for accurate pointing of the instrument. Many sorts of mounts have been developed over the years, with the majority of effort being put into systems that can track the motion of the fixed stars as the Earth rotates. == Fixed mounts == Fixed telescope mounts are entirely fixed in one position, such as Zenith telescopes that point only straight up and the National Radio Astronomy Observatory's Green Bank fixed radio 'horn' built to observe Cassiopeia A. == Fixed altitude mounts == Fixed-altitude mounts usually have the primary optics fixed at an altitude angle while rotating horizontally (in azimuth). They can cover the whole sky but only observe objects for the short time when that object passes a specific altitude and azimuth. == Transit mounts == Transit mounts are single axis mounts fixed in azimuth while rotating in altitude, usually oriented on a north-south axis. This allows the telescope to view the whole sky, but only when the Earth's rotation allows the objects to cross (transit) through that narrow north-south line (the meridian). This type of mount


id: the-porter-garden-telescope-20260505-0
file: data/en.wikipedia.org/wiki/The_Porter_Garden_Telescope-0.md
category: reference
title: The Porter Garden Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/The_Porter_Garden_Telescope
date_saved: 2026-05-05T09:48:32.433614+00:00
instance: kb-cron
parent: the-porter-garden-telescope-20260505-0
summary:
The Porter Garden Telescope was an innovative ornamental telescope for the garden designed by Russell W. Porter and commercialized by Jones & Lamson Machine Company at the beginning of the 1920s in the United States. Oriented to users with high purchasing power, and constructed in statuary bronze, it could be left permanently outdoors like sculptures and sundials, keeping the delicate optics in a case. It was embellished with floral ornament, with a style close to the art nouveau. In its base were the names of celebrated astronomers: Galileo, Kepler, and Newton. The part called the bowl bore the commercial logo "The Porter Garden Telescope", the name and address of the manufacturer, the serial number of manufacture, and the number and date of the patent. == Technical characteristics == Material of construction: Bronze. Reflecting telescope, Newtonian type. Without tube that wrap the optics. Mount: Combination of altazimuth (terrestrial use) and equatorial type horseshoe (astronomical use). Able to follow the movement of the apparent place of the stars, when it is used between the latitudes 25º-55º of both hemispheres north and south. Primary mirror of 6 inches (6": roughly 152mm). Focal relation f/4. Prism of 1.5 inches as secondary reflecting element. The


id: thirty-meter-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Thirty_Meter_Telescope-0.md
category: reference
title: Thirty Meter Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Thirty_Meter_Telescope
date_saved: 2026-05-05T09:48:33.714678+00:00
instance: kb-cron
parent: thirty-meter-telescope-20260505-0
summary:
The Thirty Meter Telescope (TMT) is a proposal for an extremely large telescope (ELT), intended to be built on Mauna Kea, on the island of Hawai'i. Scientists have been considering ELTs since the mid 1980s. In 2000, astronomers considered the possibility of a telescope with a light-gathering mirror larger than 20 meters (66 ft) in diameter, using either small segments that create one large mirror, or a grouping of larger 8-meter (26 ft) mirrors working as one unit. The US National Academy of Sciences recommended a 30-meter (98 ft) telescope be the focus of US interests, seeking to see it built within the decade. Scientists at the University of California, Santa Cruz and Caltech began development of a design that would eventually become the TMT, consisting of a 492-segment primary mirror with nine times the power of the Keck Observatory. Due to its light-gathering power and the optimal observing conditions which exist atop Mauna Kea, the TMT would enable astronomers to conduct research which is infeasible with current instruments. The TMT is designed for near-ultraviolet to mid-infrared (0.31 to 28 μm wavelengths) observations, featuring adaptive optics to assist in correcting image blur. The TMT would be at the highest altitude


id: thirty-meter-telescope-20260505-1
file: data/en.wikipedia.org/wiki/Thirty_Meter_Telescope-1.md
category: reference
title: Thirty Meter Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Thirty_Meter_Telescope
date_saved: 2026-05-05T09:48:33.714678+00:00
instance: kb-cron
parent: thirty-meter-telescope-20260505-0
summary:
Roque de los Muchachos Observatory, La Palma, Canary Islands, Spain Cerro Armazones, Antofagasta Region, Republic of Chile Cerro Tolanchar, Antofagasta Region, Republic of Chile Cerro Tolar, Antofagasta Region, Republic of Chile Mauna Kea, Hawaii, United States (This site was chosen and approval was granted in April 2013) San Pedro Mártir, Baja California, Mexico Hanle, Ladakh, India The TMT Observatory Corporation board of directors narrowed the list to two sites, one in each hemisphere, for further consideration: Cerro Armazones in Chile's Atacama Desert and Mauna Kea on Hawaii Island. On July 21, 2009, the TMT board announced Mauna Kea as the preferred site. The final TMT site selection decision was based on a combination of scientific, financial, and political criteria. Chile is also where the European Southern Observatory is building the ELT. If both next-generation telescopes were in the same hemisphere, there would be many astronomical objects that neither could observe. The telescope was given approval by the state Board of Land and Natural Resources in April 2013. There has been opposition to the building of the telescope, based on potential disruption to the fragile alpine environment of Mauna Kea due to construction, traffic, and noise, which is a concern for


id: thirty-meter-telescope-20260505-2
file: data/en.wikipedia.org/wiki/Thirty_Meter_Telescope-2.md
category: reference
title: Thirty Meter Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Thirty_Meter_Telescope
date_saved: 2026-05-05T09:48:33.714678+00:00
instance: kb-cron
parent: thirty-meter-telescope-20260505-0
summary:
Integral to the observatory is a Multi-Conjugate Adaptive Optics (MCAO) system. This MCAO system will measure atmospheric turbulence by observing a combination of natural (real) stars and artificial laser guide stars. Based on these measurements, a pair of deformable mirrors will be adjusted many times per second to correct optical wave-front distortions caused by the intervening turbulence. This system will produce diffraction-limited images over a 30-arc-second diameter field-of-view, which means that the core of the point spread function will have a size of 0.015 arc-second at a wavelength of 2.2 micrometers, almost ten times better than the Hubble Space Telescope. === Scientific instrumentation === ==== Early-light capabilities ==== Three instruments are planned to be available for scientific observations: Wide Field Optical Spectrometer (WFOS) provides a seeing limit that goes down to the ultraviolet with optical (0.3–1.0 μm wavelength) imaging and spectroscopy capable of 40-square arc-minute field-of-view. The TMT will use precision cut focal plane masks and enable long-slit observations of individual objects as well as short-slit observations of hundreds of different objects at the same time. The spectrometer will use natural (uncorrected) seeing images. Infrared Imaging Spectrometer (IRIS) mounted on the observatory MCAO system, capable of diffraction-limited imaging and integral-field


id: thirty-meter-telescope-20260505-3
file: data/en.wikipedia.org/wiki/Thirty_Meter_Telescope-3.md
category: reference
title: Thirty Meter Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Thirty_Meter_Telescope
date_saved: 2026-05-05T09:48:33.714678+00:00
instance: kb-cron
parent: thirty-meter-telescope-20260505-0
summary:
=== 2017-2019: BLNR hearings, Court validates revised permit === In March 2017, the BLNR hearing officer, retired judge Riki May Amano, finished six months of hearings in Hilo, Hawaii, taking 44 days of testimony from 71 witnesses. On July 26, 2017, Amano filed her recommendation that the Land Board grant the construction permit. On September 28, 2017, the BLNR, acting on Amano's report, approved, by a vote of 5-2, a Conservation District Use Permit (CDUP) for the TMT. Numerous conditions, including the removal of three existing telescopes and an assertion that the TMT is to be the last telescope on the mountain, were attached to the permit. On October 30, 2018, the Supreme Court of Hawaii ruled 4-1, that the revised permit was acceptable, allowing construction to proceed. On July 10, 2019, Hawaii Gov. David Ige and the Thirty Meter Telescope International Observatory jointly announced that construction would begin the week of July 15, 2019. === 2019 blockade and aftermath === On July 15, 2019, renewed protests blocked the access road, again preventing construction from commencing. On July 17, 38 protestors were arrested, all of whom were kupuna (elders) as the blockage of the access road continued. The blockade lasted


id: thirty-meter-telescope-20260505-4
file: data/en.wikipedia.org/wiki/Thirty_Meter_Telescope-4.md
category: reference
title: Thirty Meter Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Thirty_Meter_Telescope
date_saved: 2026-05-05T09:48:33.714678+00:00
instance: kb-cron
parent: thirty-meter-telescope-20260505-0
summary:
== Alternative site in the Canary Islands == In response to the ongoing protests that occurred in July 2019, the TMT project officials requested a building permit for a second site choice, the Spanish Observatorio del Roque de los Muchachos on the island of La Palma in the Canary Islands. Rafael Rebolo, the director of the Instituto de Astrofísica de Canarias, confirmed that he had received a letter requesting a building permit for the site as a backup in case the Hawaii site cannot be constructed. Some astronomers argue however that La Palma is not an adequate site to build the telescope due to the island’s comparatively low elevation, which would enable water vapor to frequently interfere with observations due to water vapor’s tendency to absorb light at midinfrared wavelengths. Such atmospheric interference could impact observing times for research into exoplanets, galactic formation, and cosmology. Other astronomers argue that construction of the telescope in La Palma would disrupt projected international collaboration between the United States and other involved countries such as Japan, Canada, and India. Environmentalists such as Ben Magec and the environmental advocacy organization Ecologistas en Acción in the Canary Islands geared up to oppose its construction there as


id: timeline-of-telescope-technology-20260505-0
file: data/en.wikipedia.org/wiki/Timeline_of_telescope_technology-0.md
category: reference
title: Timeline of telescope technology
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Timeline_of_telescope_technology
date_saved: 2026-05-05T09:48:34.990249+00:00
instance: kb-cron
parent: timeline-of-telescope-technology-20260505-0
summary:
The following timeline lists the significant events in the invention and development of the telescope. == BC == === 2560 BC to 1 BC === c.2560 BC–c.860 BC — Egyptian artisans polish rock crystal, semi-precious stones, and latterly glass to produce facsimile eyes for statuary and mummy cases. The intent appears to be to produce an optical illusion. 424 BC Aristophanes "lens" is a glass globe filled with water.(Seneca says that it can be used to read letters no matter how small or dim) 3rd century BC Euclid is the first to study reflection and refraction using mathematical theorems based on the fact that light travels in straight lines == AD == === 1 AD to 999 AD === 2nd century AD — Ptolemy (in his work Optics) wrote about the properties of light including: reflection, refraction, and colour. 984 — Ibn Sahl completes a treatise On Burning Mirrors and Lenses, describing plano-convex and biconvex lenses, and parabolic and ellipsoidal mirrors. === 1000 AD to 1999 AD === 1011–1021 — Ibn al-Haytham (also known as Alhacen or Alhazen) writes the Kitab al-Manazir (Book of Optics) 1230–1235 — Robert Grosseteste describes the use of 'optics' to "...make small things placed at


id: timeline-of-telescope-technology-20260505-1
file: data/en.wikipedia.org/wiki/Timeline_of_telescope_technology-1.md
category: reference
title: Timeline of telescope technology
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Timeline_of_telescope_technology
date_saved: 2026-05-05T09:48:34.990249+00:00
instance: kb-cron
parent: timeline-of-telescope-technology-20260505-0
summary:
1668 — Isaac Newton produces the first functioning reflecting telescope using a spherical primary mirror and a flat diagonal secondary mirror. This design is termed the 'Newtonian'. 1672 — Laurent Cassegrain, produces a design for a reflecting telescope using a paraboloid primary mirror and a hyperboloid secondary mirror. The design, named 'Cassegrain', is still used in astronomical telescopes used in observatories in 2006. 1674 — Robert Hooke produces a reflecting telescope based on the Gregorian design. 1684 — Christiaan Huygens publishes "Astroscopia Compendiaria" in which he described the design of very long aerial telescopes. 1720 — John Hadley develops ways of aspherizing spherical mirrors to make very accurate parabolic mirrors and produces a much improved Gregorian telescope 1721 — John Hadley experiments with the neglected Newtonian telescope design and demonstrates one with a 6-inch parabolic mirror to the Royal Society. 1730s — James Short succeeds in producing a Gregorian telescopes to true paraboloidal primary and ellipsoidal secondary design specifications. 1733 — Chester Moore Hall invents the achromatic lens. 1758 — John Dollond re-invents and patents the achromatic lens. 1783 — Jesse Ramsden invents his eponymous eyepiece. 1803 — The "Observatorio Astronómico Nacional de Colombia (OAN)" is inaugurated as the first


id: timeline-of-telescopes-observatories-and-observing-technology-20260505-0
file: data/en.wikipedia.org/wiki/Timeline_of_telescopes,_observatories,_and_observing_technology-0.md
category: reference
title: Timeline of telescopes, observatories, and observing technology
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Timeline_of_telescopes,_observatories,_and_observing_technology
date_saved: 2026-05-05T09:48:36.155717+00:00
instance: kb-cron
parent: timeline-of-telescopes-observatories-and-observing-technology-20260505-0
summary:
Timeline of telescopes, observatories, and observing technology. == Before the Common Era (BCE) == === 1900s BCE === Taosi Astronomical Observatory, Xiangfen County, Linfen City, Shanxi Province, China === 1500s BCE === Shadow clocks invented in ancient Egypt and Mesopotamia === 600s BCE === 11th–7th century BCE, Zhou dynasty astronomical observatory (灵台) in Fenghao (today's Xi'an), China === 200s BCE === Thirteen Towers solar observatory, Chankillo, Peru Antikythera Mechanism, a geared astronomical computer that calculates lunar and solar eclipses, the position of the Sun and the Moon the lunar phase (age of the Moon as seen from Earth), has several lunisolar calendars, including the Olympic Games calendar. It is at the National Archaeological Museum, Athens, Greece. === 100s BCE === 220-206 BCE, Han dynasty astronomical observatory (灵台) in Chang'an and Luoyang. During East Han dynasty, astronomical observatory (灵台) built in Yanshi, Henan Province, China 220-150 BCE, Astrolabe invented by Apollonius of Perga == Common Era (CE) == === 400s === 5th century – Observatory at Ujjain, India === 600s === 632–647 – Cheomseongdae observatory is built in the reign of Queen Seondeok at Gyeongju, then the capital of Silla (present day South Korea) 618–1279 – Tang dynasty-Song dynasty, observatories built


id: timeline-of-telescopes-observatories-and-observing-technology-20260505-1
file: data/en.wikipedia.org/wiki/Timeline_of_telescopes,_observatories,_and_observing_technology-1.md
category: reference
title: Timeline of telescopes, observatories, and observing technology
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Timeline_of_telescopes,_observatories,_and_observing_technology
date_saved: 2026-05-05T09:48:36.155717+00:00
instance: kb-cron
parent: timeline-of-telescopes-observatories-and-observing-technology-20260505-0
summary:
=== 1800s === 1803 National Astronomical Observatory (Colombia), the first observatory in the Americas 1836 Swathithirunal opened Trivandrum observatory 1839 Louis Jacques Mandé Daguerre (inventor of the daguerreotype photographic process) attempts to photograph the moon. Tracking errors in guiding the telescope during the long exposure made the photograph came out as an indistinct fuzzy spot 1840 – John William Draper takes make a successful photographic image of the Moon, the first astronomical photograph 1845 – Lord Rosse finishes the Birr Castle 72-inch (1.8 m) optical reflecting telescope, located in Parsonstown, Ireland 1849 – Santiago observatory set up by USA, later becomes Chilean National Observatory (now part of the University of Chile) 1859 – Kirchhoff and Bunsen develop spectroscopy 1864 – Herschel's so-called GC (General Catalogue) of nebulae and star clusters published 1868 – Janssen and Lockyer discover Helium observing spectra of the Sun 1871 – German Astronomical Association organized network of 13 (later 16) observatories for stellar proper motion studies 1863 – William Allen Miller and Sir William Huggins use the photographic wet collodion plate process to obtain the first ever photographic spectrogram of a star, Sirius and Capella. 1872 – Henry Draper photographs a spectrum of Vega that shows


id: timeline-of-telescopes-observatories-and-observing-technology-20260505-2
file: data/en.wikipedia.org/wiki/Timeline_of_telescopes,_observatories,_and_observing_technology-2.md
category: reference
title: Timeline of telescopes, observatories, and observing technology
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Timeline_of_telescopes,_observatories,_and_observing_technology
date_saved: 2026-05-05T09:48:36.155717+00:00
instance: kb-cron
parent: timeline-of-telescopes-observatories-and-observing-technology-20260505-0
summary:
==== 1970s ==== 1970 – Cerro Tololo 158-inch (4.0 m) optical reflecting telescope begins operation, located in Cerro Tololo, Chile 1970 – Kitt Peak National Observatory 158-inch (4.0 m) optical reflecting telescope begins operation, located near Tucson, Arizona 1970 – Uhuru x-ray telescope satellite 1970 – Antoine Labeyrie performs the first high-resolution optical speckle interferometry observations 1970 – Westerbork Synthesis Radio Telescope completed, near Westerbork, Netherlands 1972 – 100 m Effelsberg radio telescope inaugurated (Germany) 1973 – UK Schmidt Telescope 1.2 metre optical reflecting telescope begins operation, located in Anglo-Australian Observatory near Coonabarabran, Australia 1974 – Anglo-Australian Telescope 153-inch (3.9 m) optical reflecting telescope begins operation, located in Anglo-Australian Observatory near Coonabarabran, Australia 1975 – Gerald Smith, Frederick Landauer, and James Janesick use a CCD to observe Uranus, the first astronomical CCD observation 1975 – Antoine Labeyrie builds the first two-telescope optical interferometer 1976 – The 6-m BTA-6 (Bolshoi Teleskop Azimutalnyi or “Large Altazimuth Telescope”) goes into operation on Mt. Pashtukhov in the Russian Caucasus 1978 – Multiple Mirror 176-inch (4.5 m) equivalent optical/infrared reflecting telescope begins operation, located in Amado, Arizona 1978 – International Ultraviolet Explorer (IUE) telescope satellite 1978 – Einstein High Energy Astronomy Observatory x-ray telescope satellite


id: tpoint-20260505-0
file: data/en.wikipedia.org/wiki/Tpoint-0.md
category: reference
title: Tpoint
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Tpoint
date_saved: 2026-05-05T09:48:37.334647+00:00
instance: kb-cron
parent: tpoint-20260505-0
summary:
TPoint is computer software that implements a mathematical model of conditions leading to errors in telescope pointing and tracking. The model can then be used in a telescope control system to correct the pointing and tracking. Such errors are typically caused by mechanical or structural defects. For example, TPoint can analyze and compensate for systematic errors such as polar misalignment, mechanical and optical non-orthogonality, lack of roundness in telescope mounting drive gears, as well as for flexure of the mounting caused by gravity. TPoint is in use on the majority of professional telescopes worldwide, including among many others the Anglo-Australian Telescope, Keck Observatory, Gemini Observatory and the Large Binocular Telescope. It has significantly improved the performance and efficiency of telescope operation and has had an especially strong impact on the development of automated and robotic telescopes. TPoint is also widely used by amateur astronomers. Software Bisque distributes TPoint as an add-on to TheSkyX Serious Astronomer Edition and TheSkyX Professional; this version is used to improve the pointing on amateur telescopes. == History == TPoint was invented and developed by Patrick Wallace. It grew out of work he and John Straede performed at the Anglo-Australian Telescope (AAT) between 1974 and 1980


id: transient-array-radio-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Transient_Array_Radio_Telescope-0.md
category: reference
title: Transient Array Radio Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transient_Array_Radio_Telescope
date_saved: 2026-05-05T09:48:38.538730+00:00
instance: kb-cron
parent: transient-array-radio-telescope-20260505-0
summary:
The Transient Array Radio Telescope (TART) is a low-cost open-source array radio telescope consisting of 24 all-sky GNSS receivers operating at the L1-band (1.575 GHz). TART was designed as an all-sky survey instrument for detecting radio bursts, as well as providing a test-bed for the development of new synthesis imaging and calibration algorithms. All of the telescope hardware including radio receivers, correlators and operating software are open source. A TART-2 radio-telescope can be built for approximately 1000 Euros, and the telescope antenna array requires 4m x 4m area for deployment. The TART project is managed by the Electronics Research Foundation, a non-profit based in New Zealand. == Design == All of the components of TART, from the hardware, FPGA firmware and the operation and imaging software are open source. released under the GPLv3 license. A TART radio telescope consists of four main sub-assemblies, the antenna array, RF Front End, radio Hub and basestation. === Antenna array === The antenna array consists of 24 antennas arranged on four identical 'tiles' with 6 antennas each. Each tile is a 1x1 meter square. The antennas used are low-cost, widely available commercial GPS active antennas. More recent installations use multi-arm antenna arrays in either


id: unistellar-20260505-0
file: data/en.wikipedia.org/wiki/Unistellar-0.md
category: reference
title: Unistellar
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Unistellar
date_saved: 2026-05-05T09:48:39.767085+00:00
instance: kb-cron
parent: unistellar-20260505-0
summary:
Unistellar is a French manufacturer of computer-connected telescopes that allow non-professional skywatchers to observe astronomical objects at relatively low cost. The first product launched was named the eVscope, and used digital astrophotographic techniques. SETI Institute has partnered with Unistellar and will be able to send requests for information and notifications to users, and receive information about transient astronomical events. == History == The company was founded in Marseille, France, in 2015, with incubator investment from Incubateur Impulse and Pépinières d'Entreprises Innovantes with subsequent VC round capital from private investors and a VC firm named Brighteye Ventures. Unistellar unveiled their electronic telescope technology prototype in 2017 at CES2017 in Las Vegas and at IFA Next in Berlin. The company experienced difficulties bringing the product to market. The consumer-grade electronic telescope was originally planned to be available in the "fall 2018" which subsequently shifted to "early 2019," then later in 2019. By January 2020, the telescope was expected to be shipped worldwide between May and August 2020. As of December 2021, over 5000 telescopes had been delivered to customers The kit included a custom tripod and mount, a Bahtinov mask and a protective cap. Later, Unistellar introduced two new telescopes, eVscope 2


id: vacuum-tower-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Vacuum_Tower_Telescope-0.md
category: reference
title: Vacuum Tower Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Vacuum_Tower_Telescope
date_saved: 2026-05-05T09:48:40.940941+00:00
instance: kb-cron
parent: vacuum-tower-telescope-20260505-0
summary:
The Vacuum Tower Telescope (VTT) is an evacuated-optics solar telescope located at the Teide Observatory on Tenerife in the Canary Islands. It is operated by the Kiepenheuer-Institut für Sonnenphysik (KIS). It was built between 1983 and 1986, with first light in 1988. It has a 70-centimetre-diameter (28 in) primary mirror and a focal length of 46 metres (151 ft). Thanks to an adaptive optics system KAOS (Kiepenheuer-institute Adaptive Optic System), in operation since spring 2000, it is able to resolve details down to 0.2 arc seconds (150 km) on the Sun's surface. == Description == The VTT and the GREGOR are operated by four German institutes: the Astrophysikalisches Institut Potsdam, the Kiepenheuer-Institut für Sonnenphysik (Freiburg, chair), the Max-Planck-Institut für Sonnensystemforschung (Lindau), and the Universitäts-Sternwarte Göttingen. The telescope is used for scientific observations from mid-April through mid-December. Typically 30 to 40 observing campaigns are carried out every year. == History == In the early seventies, the 40-centimetre Newton telescope, built at the Kiepenheuer-Institut, was installed at the Observatorio del Teide. In 1982, the Federal Republic of Germany joined the international Agreement on the Cooperation in Astrophysical Research between Spain, Great Britain, Sweden and Denmark. Construction work for the German solar telescopes


id: zoom-lens-20260505-0
file: data/en.wikipedia.org/wiki/Zoom_lens-0.md
category: reference
title: Zoom lens
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Zoom_lens
date_saved: 2026-05-05T09:48:43.309513+00:00
instance: kb-cron
parent: zoom-lens-20260505-0
summary:
A zoom lens is a system of camera lens elements for which the focal length (and thus angle of view) can be varied, as opposed to a fixed-focal-length (FFL) lens (prime lens). A true zoom lens or optical zoom lens is a type of parfocal lens, one that maintains focus when its focal length changes. Most consumer zoom lenses do not maintain perfect focus, but are still nearly parfocal. Most camera phones that are advertised as having optical zoom actually use a few cameras of different but fixed focal length, combined with digital zoom to make a hybrid system. The convenience of variable focal length comes at the cost of complexity – and some compromises on image quality, weight, dimensions, aperture, autofocus performance, and cost. For example, all zoom lenses suffer from at least slight, if not considerable, loss of image resolution at their maximum aperture, especially at the extremes of their focal length range. This effect is evident in the corners of the image, when displayed in a large format or high resolution. The greater the range of focal length a zoom lens offers, the more exaggerated these compromises must become. == Characteristics == Zoom lenses are often described


id: zoom-lens-20260505-1
file: data/en.wikipedia.org/wiki/Zoom_lens-1.md
category: reference
title: Zoom lens
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Zoom_lens
date_saved: 2026-05-05T09:48:43.309513+00:00
instance: kb-cron
parent: zoom-lens-20260505-0
summary:
The Kilfitt 36–82 mm/2.8 Zoomar lens introduced in 1959 was the first varifocal lens in regular production for still 35mm photography. The first modern film zoom lens, the Pan-Cinor, was designed around 1950 by Roger Cuvillier, a French engineer working for SOM-Berthiot. It had an optical compensation zoom system. In 1956, Pierre Angénieux introduced the mechanical compensation system, enabling precise focus while zooming, in his 17-68mm lens for 16mm released in 1958. The same year a prototype of the 35mm version of the Angénieux 4x zoom, the 35-140mm was first used by cinematographer Roger Fellous for the production of Julie La Rousse. Angénieux received a 1964 technical award from the academy of motion pictures for the design of the 10 to 1 zoom lenses, including the 12-120mm for 16mm film cameras and the 25-250mm for 35mm film cameras. Because of their relative bulk, it wasn't until as recently as 1986 that a zoom lens was designed with sufficiently compact dimensions and finally found its way into a consumer compact (point and shoot) camera, this being the Pentax Zoom 70. Since then advances in optical lens design, particularly the use of computers for optical ray tracing, has made the design and


id: design-of-experiments-20260505-0
file: data/en.wikipedia.org/wiki/Design_of_experiments-0.md
category: reference
title: Design of experiments
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Design_of_experiments
date_saved: 2026-05-05T09:48:44.910356+00:00
instance: kb-cron
parent: design-of-experiments-20260505-0
summary:
The design of experiments (DOE), also known as experiment design or experimental design, is the design of any task that aims to describe and explain the variation of information under conditions that are hypothesized to reflect the variation. The term is generally associated with experiments in which the design introduces conditions that directly affect the variation, but may also refer to the design of quasi-experiments, in which natural conditions that influence the variation are selected for observation. In its simplest form, an experiment aims at predicting the outcome by introducing a change of the preconditions, which is represented by one or more independent variables, also referred to as "input variables" or "predictor variables." The change in one or more independent variables is generally hypothesized to result in a change in one or more dependent variables, also referred to as "output variables" or "response variables." The experimental design may also identify control variables that must be held constant to prevent external factors from affecting the results. Experimental design involves not only the selection of suitable independent, dependent, and control variables, but planning the delivery of the experiment under statistically optimal conditions given the constraints of available resources. There are multiple approaches


id: design-of-experiments-20260505-1
file: data/en.wikipedia.org/wiki/Design_of_experiments-1.md
category: reference
title: Design of experiments
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Design_of_experiments
date_saved: 2026-05-05T09:48:44.910356+00:00
instance: kb-cron
parent: design-of-experiments-20260505-0
summary:
Comparison In some fields of study it is not possible to have independent measurements to a traceable metrology standard. Comparisons between treatments are much more valuable and are usually preferable, and often compared against a scientific control or traditional treatment that acts as baseline. Randomization Random assignment is the process of assigning individuals at random to groups or to different groups in an experiment, so that each individual of the population has the same chance of becoming a participant in the study. The random assignment of individuals to groups (or conditions within a group) distinguishes a rigorous, "true" experiment from an observational study or "quasi-experiment". There is an extensive body of mathematical theory that explores the consequences of making the allocation of units to treatments by means of some random mechanism (such as tables of random numbers, or the use of randomization devices such as playing cards or dice). Assigning units to treatments at random tends to mitigate confounding, which makes effects due to factors other than the treatment to appear to result from the treatment. The risks associated with random allocation (such as having a serious imbalance in a key characteristic between a treatment group and a control group)


id: design-of-experiments-20260505-2
file: data/en.wikipedia.org/wiki/Design_of_experiments-2.md
category: reference
title: Design of experiments
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Design_of_experiments
date_saved: 2026-05-05T09:48:44.910356+00:00
instance: kb-cron
parent: design-of-experiments-20260505-0
summary:
Let yi be the measured difference for i = 1, ..., 8. The relationship between the true weights and experimental measurements may be represented with a general linear model, with the design matrix W {\displaystyle W} having entries from { − 1 , 0 , 1 } {\displaystyle \{-1,0,1\}} : y = W θ + ϵ {\displaystyle y=W\theta +\epsilon } The first design is represented by an identity matrix while the second design is represented by an 8x8 Hadamard matrix, H {\displaystyle H} , both examples of weighing matrices. The weights are typically estimated using the method of least squares. Using a weighing matrix, this is equivalent to inverting on the measurements: θ ^ A = I − 1 y = y {\displaystyle {\hat {\theta }}_{A}=I^{-1}y=y} θ ^ B = H − 1 y {\displaystyle {\hat {\theta }}_{B}=H^{-1}y} The question of design of experiments is: which experiment is better? Investigating estimate A vs B for the first weight: Var ⁡ ( θ ^ A , 1 ) = Var ⁡ ( y 1 ) = σ 2 {\displaystyle \operatorname {Var} ({\hat {\theta }}_{A,1})=\operatorname {Var} (y_{1})=\sigma ^{2}} Var ⁡ ( θ ^ B , 1 ) = Var ⁡ ( y


id: design-of-experiments-20260505-3
file: data/en.wikipedia.org/wiki/Design_of_experiments-3.md
category: reference
title: Design of experiments
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Design_of_experiments
date_saved: 2026-05-05T09:48:44.910356+00:00
instance: kb-cron
parent: design-of-experiments-20260505-0
summary:
== Causal attributions == In the pure experimental design, the independent (predictor) variable is manipulated by the researcher – that is – every participant of the research is chosen randomly from the population, and each participant chosen is assigned randomly to conditions of the independent variable. Only when this is done is it possible to certify with high probability that the reason for the differences in the outcome variables are caused by the different conditions. Therefore, researchers should choose the experimental design over other design types whenever possible. However, the nature of the independent variable does not always allow for manipulation. In those cases, researchers must be aware of not certifying about causal attribution when their design doesn't allow for it. For example, in observational designs, participants are not assigned randomly to conditions, and so if there are differences found in outcome variables between conditions, it is likely that there is something other than the differences between the conditions that causes the differences in outcomes, that is – a third variable. The same goes for studies with correlational design. == Statistical control == It is best that a process be in reasonable statistical control prior to conducting designed experiments. When


id: design-of-experiments-20260505-4
file: data/en.wikipedia.org/wiki/Design_of_experiments-4.md
category: reference
title: Design of experiments
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Design_of_experiments
date_saved: 2026-05-05T09:48:44.910356+00:00
instance: kb-cron
parent: design-of-experiments-20260505-0
summary:
== See also == Adversarial collaboration – Method of research Bayesian experimental design – Experimental design framework Block design – Structure in combinatorial mathematics Box–Behnken design – Experimental designs for response surface methodology Central composite design – Experimental design in statistical mathematics Clinical study design – Plan for research in clinical medicine Computer experiment – Experiment used to study computer simulation Controlling for a variable – Binning data according to measured values of the variable Experimetrics (econometrics-related experiments) Factor analysis – Statistical method Fractional factorial design – Statistical experimental design approach Glossary of experimental design Grey box model – Mathematical data production model with limited structure Industrial engineering – Branch of engineering which deals with the optimization of complex processes or systems Instrument effect Law of large numbers – Averages of repeated trials converge to the expected value Manipulation checks Multifactor design of experiments software One-factor-at-a-time method – Method of designing experiments Optimal design – Experimental design that is optimal with respect to some statistical criterionPages displaying short descriptions of redirect targets Plackett–Burman design – Type of experimental design Probabilistic design – Discipline within engineering design Protocol (natural sciences) – Procedural method for the design and implementation of an experimentPages


id: adaptive-design-medicine-20260505-0
file: data/en.wikipedia.org/wiki/Adaptive_design_(medicine)-0.md
category: reference
title: Adaptive design (medicine)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Adaptive_design_(medicine)
date_saved: 2026-05-05T09:48:46.125163+00:00
instance: kb-cron
parent: adaptive-design-medicine-20260505-0
summary:
In an adaptive design of a clinical trial, the parameters and conduct of the trial for a candidate drug or vaccine may be changed based on an interim analysis. Adaptive design typically involves advanced statistics to interpret a clinical trial endpoint. This is in contrast to traditional single-arm (i.e. non-randomized) clinical trials or randomized clinical trials (RCTs) that are static in their protocol and do not modify any parameters until the trial is completed. The adaptation process takes place at certain points in the trial, prescribed in the trial protocol. Importantly, this trial protocol is set before the trial begins with the adaptation schedule and processes specified. Adaptions may include modifications to: dosage, sample size, drug undergoing trial, patient selection criteria and/or "cocktail" mix. The PANDA (A Practical Adaptive & Novel Designs and Analysis toolkit) provides not only a summary of different adaptive designs, but also comprehensive information on adaptive design planning, conduct, analysis and reporting. == Purpose == The aim of an adaptive trial is to more quickly identify drugs or devices that have a therapeutic effect, and to zero in on patient populations for whom the drug is appropriate. When conducted efficiently, adaptive trials have the potential to


id: adaptive-design-medicine-20260505-1
file: data/en.wikipedia.org/wiki/Adaptive_design_(medicine)-1.md
category: reference
title: Adaptive design (medicine)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Adaptive_design_(medicine)
date_saved: 2026-05-05T09:48:46.125163+00:00
instance: kb-cron
parent: adaptive-design-medicine-20260505-0
summary:
=== Group sequential design === Group sequential design is the application of sequential analysis to clinical trials. At each interim analysis, investigators will use the current data to decide whether the trial should either stop or should continue to recruit more participants. The trial might stop either because the evidence that the treatment is working is strong ("stopping for benefit") or weak ("stopping for futility"). Whether a trial may stop for futility only, benefit only, or either, is stated in advance. A design has "binding stopping rules" when the trial must stop when a particular threshold of (either strong or weak) evidence is crossed at a particular interim analysis. Otherwise it has "non-binding stopping rules", in which case other information can be taken into account, for example safety data. The number of interim analyses is specified in advance, and can be anything from a single interim analysis (a "two-stage" design") to an interim analysis after every participant ("continuous monitoring"). For trials with a binary (response/no response) outcome and a single treatment arm, a popular and simple group sequential design with two stages is the Simon design. In this design, there is a single interim analysis partway through the trial, at


id: adaptive-design-medicine-20260505-2
file: data/en.wikipedia.org/wiki/Adaptive_design_(medicine)-2.md
category: reference
title: Adaptive design (medicine)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Adaptive_design_(medicine)
date_saved: 2026-05-05T09:48:46.125163+00:00
instance: kb-cron
parent: adaptive-design-medicine-20260505-0
summary:
==== I-SPY 1 ==== For its predecessor I-SPY 1, 10 cancer centers and the National Cancer Institute (NCI SPORE program and the NCI Cooperative groups) collaborated to identify response indicators that would best predict survival for women with high-risk breast cancer. During 2002–2006, the study monitored 237 patients undergoing neoadjuvant therapy before surgery. Iterative MRI and tissue samples monitored the biology of patients to chemotherapy given in a neoadjuvant setting, or presurgical setting. Evaluating chemotherapy's direct impact on tumor tissue took much less time than monitoring outcomes in thousands of patients over long time periods. The approach helped to standardize the imaging and tumor sampling processes, and led to miniaturized assays. Key findings included that tumor response was a good predictor of patient survival, and that tumor shrinkage during treatment was a good predictor of long-term outcome. Importantly, the vast majority of tumors identified as high risk by molecular signature. However, heterogeneity within this group of women and measuring response within tumor subtypes was more informative than viewing the group as a whole. Within genetic signatures, level of response to treatment appears to be a reasonable predictor of outcome. Additionally, its shared database has furthered the understanding of drug response


id: adaptive-design-medicine-20260505-3
file: data/en.wikipedia.org/wiki/Adaptive_design_(medicine)-3.md
category: reference
title: Adaptive design (medicine)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Adaptive_design_(medicine)
date_saved: 2026-05-05T09:48:46.125163+00:00
instance: kb-cron
parent: adaptive-design-medicine-20260505-0
summary:
For regulatory submission of Bayesian clinical trial design, there exist two Bayesian decision rules that are frequently used by trial sponsors. First, posterior probability approach is mainly used in decision-making to quantify the evidence to address the question, "Does the current data provide convincing evidence in favor of the alternative hypothesis?" The key quantity of the posterior probability approach is the posterior probability of the alternative hypothesis being true based on the data observed up to the point of analysis. Second, predictive probability approach is mainly used in decision-making is to answer the question at an interim analysis: "Is the trial likely to present compelling evidence in favor of the alternative hypothesis if we gather additional data, potentially up to the maximum sample size (or current sample size)?" The key quantity of the predictive probability approach is the posterior predictive probability of the trial success given the interim data. In most regulatory submissions, Bayesian trial designs are calibrated to possess good frequentist properties. In this spirit, and in adherence to regulatory practice, regulatory agencies typically recommend that sponsors provide the frequentist type I and II error rates for the sponsor's proposed Bayesian analysis plan. In other words, the Bayesian designs


id: adversarial-collaboration-20260505-0
file: data/en.wikipedia.org/wiki/Adversarial_collaboration-0.md
category: reference
title: Adversarial collaboration
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Adversarial_collaboration
date_saved: 2026-05-05T09:48:47.307037+00:00
instance: kb-cron
parent: adversarial-collaboration-20260505-0
summary:
In science, adversarial collaboration is a modality of collaboration wherein opposing views work together in order to jointly advance knowledge of the area under dispute. This can take the form of a scientific experiment conducted by two groups of experimenters with competing hypotheses, with the aim of constructing and implementing an experimental design in a way that satisfies both groups that there are no obvious biases or weaknesses in the experimental design. Adversarial collaboration can involve a neutral moderator and lead to a co-designed experiment and joint publishing of findings in order to resolve differences. With its emphasis on transparency throughout the research process, adversarial collaboration has been described as sitting within the open science framework. == History == One of the earliest modern examples of adversarial collaboration was a 1988 collaboration between Erez and Latham with Edwin Locke working as a neutral third party. This collaboration came about as the result of a disagreement from the field of Goal-Setting research between Erez and Latham on an aspect of goal-setting research around the effect of participation on goal commitment and performance. Latham and Erez designed four experiments which explained the differences between their individual findings, but did not coin the


id: age-adjustment-20260505-0
file: data/en.wikipedia.org/wiki/Age_adjustment-0.md
category: reference
title: Age adjustment
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Age_adjustment
date_saved: 2026-05-05T09:48:48.499475+00:00
instance: kb-cron
parent: age-adjustment-20260505-0
summary:
In epidemiology and demography, age adjustment, also called age standardization, is a technique used to allow statistical populations to be compared when the age profiles of the populations are quite different. == Example == For example, in 2004/5, two Australian health surveys investigated rates of long-term circulatory system health problems (e.g. heart disease) in the general Australian population, and specifically in the Indigenous Australian population. In each age category over age 24, Indigenous Australians had markedly higher rates of circulatory disease than the general population: 5% vs 2% in age group 25–34, 12% vs 4% in age group 35–44, 22% vs 14% in age group 45–54, and 42% vs 33% in age group 55+. However, overall, these surveys estimated that 12% of all Indigenous Australians had long-term circulatory problems compared to 18% of the overall Australian population. == Standard populations == In order to adjust for age, a standard population must be selected. Some agencies which produce health statistics also publish standard populations for age adjustment. Standard populations have been developed for specific countries and regions. World standard populations have also been developed to compare data from different countries, including the Segi World Standard and the World Health Organization (WHO)


id: aliasing-factorial-experiments-20260505-0
file: data/en.wikipedia.org/wiki/Aliasing_(factorial_experiments)-0.md
category: reference
title: Aliasing (factorial experiments)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Aliasing_(factorial_experiments)
date_saved: 2026-05-05T09:48:49.670316+00:00
instance: kb-cron
parent: aliasing-factorial-experiments-20260505-0
summary:
In the statistical theory of factorial experiments, aliasing is the property of fractional factorial designs that makes some effects "aliased" with each other – that is, indistinguishable from each other. A primary goal of the theory of such designs is the control of aliasing so that important effects are not aliased with each other. In a "full" factorial experiment, the number of treatment combinations or cells (see below) can be very large. This necessitates limiting observations to a fraction (subset) of the treatment combinations. Aliasing is an automatic and unavoidable result of observing such a fraction. The aliasing properties of a design are often summarized by giving its resolution. This measures the degree to which the design avoids aliasing between main effects and important interactions. Fractional factorial experiments have long been a basic tool in agriculture, food technology, industry, medicine and public health, and the social and behavioral sciences. They are widely used in exploratory research, particularly in screening experiments, which have applications in industry, drug design and genetics. In all such cases, a crucial step in designing such an experiment is deciding on the desired aliasing pattern, or at least the desired resolution. As noted below, the concept of


id: aliasing-factorial-experiments-20260505-1
file: data/en.wikipedia.org/wiki/Aliasing_(factorial_experiments)-1.md
category: reference
title: Aliasing (factorial experiments)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Aliasing_(factorial_experiments)
date_saved: 2026-05-05T09:48:49.670316+00:00
instance: kb-cron
parent: aliasing-factorial-experiments-20260505-0
summary:
== Definitions == The factors in the design are allowed to have different numbers of levels, as in a 2 × 3 × 3 {\displaystyle 2\times 3\times 3} factorial experiment (an asymmetric or mixed-level experiment). Fix a fraction of a full factorial design. Let U {\displaystyle U} be a set of contrast vectors representing an effect (in particular, a main effect or interaction) in the full factorial design, and let U ~ {\displaystyle {\widetilde {U}}} consist of the restrictions of those vectors to the fraction. One says that the effect is preserved in the fraction if U ~ {\displaystyle {\widetilde {U}}} consists of contrast vectors; completely lost in the fraction if U ~ {\displaystyle {\widetilde {U}}} consists of constant vectors, that is, vectors whose components are equal; and partly lost otherwise. Similarly, let U 1 {\displaystyle U_{1}} and U 2 {\displaystyle U_{2}} represent two effects and let U ~ 1 {\displaystyle {\widetilde {U}}_{1}} and U ~ 2 {\displaystyle {\widetilde {U}}_{2}} be their restrictions to the fraction. The two effects are said to be unaliased in the fraction if each vector in U ~ 1 {\displaystyle {\widetilde {U}}_{1}} is orthogonal (perpendicular) to all the vectors in U ~ 2 {\displaystyle {\widetilde


id: aliasing-factorial-experiments-20260505-2
file: data/en.wikipedia.org/wiki/Aliasing_(factorial_experiments)-2.md
category: reference
title: Aliasing (factorial experiments)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Aliasing_(factorial_experiments)
date_saved: 2026-05-05T09:48:49.670316+00:00
instance: kb-cron
parent: aliasing-factorial-experiments-20260505-0
summary:
=== The 2 × 2 × 2 (or 2³) experiment === This is a "two-level" experiment with factors A , B {\displaystyle A,B} and C {\displaystyle C} . In such experiments the factor levels are often denoted by 0 and 1, for reasons explained below. A treatment combination is then denoted by an ordered triple such as 101 (more formally, (1, 0, 1), denoting the cell in which A {\displaystyle A} and C {\displaystyle C} are at level "1" and B {\displaystyle B} is at level "0"). The following table lists the eight cells of the full 2 × 2 × 2 factorial experiment, along with a contrast vector representing each effect, including a three-factor interaction: Suppose that only the fraction consisting of the cells 000, 011, 101, and 110 is observed. The original contrast vectors, when restricted to these cells, are now 4 × 1, and can be seen by looking at just those four rows of the table. (Sorting the table on A B C {\displaystyle ABC} will bring these rows together and make the restricted contrast vectors easier to see. Sorting twice puts them at the top.) The following can be observed concerning these restricted vectors: The


id: aliasing-factorial-experiments-20260505-3
file: data/en.wikipedia.org/wiki/Aliasing_(factorial_experiments)-3.md
category: reference
title: Aliasing (factorial experiments)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Aliasing_(factorial_experiments)
date_saved: 2026-05-05T09:48:49.670316+00:00
instance: kb-cron
parent: aliasing-factorial-experiments-20260505-0
summary:
where the equation is modulo s {\displaystyle s} if s {\displaystyle s} is prime, and is in the finite field G F ( s ) {\displaystyle GF(s)} if s {\displaystyle s} is a power of a prime. Such equations are called defining equations of the fraction. When the defining equation or equations are homogeneous, the fraction is said to be principal. One defining equation yields a fraction of size s k − 1 {\displaystyle s^{k-1}} , two independent equations a fraction of size s k − 2 , {\displaystyle s^{k-2},} and so on. Such fractions are generally denoted as s k − r {\displaystyle s^{k-r}} designs. The half-fractions described above are 2 3 − 1 {\displaystyle 2^{3-1}} designs. The notation often includes the resolution as a subscript, in Roman numerals; the above fractions are thus 2 I I I 3 − 1 {\displaystyle 2_{III}^{3-1}} designs. Associated to each expression a 1 t 1 + ⋯ + a k t k {\displaystyle a_{1}t_{1}+\cdots +a_{k}t_{k}} is another, namely A 1 a 1 ⋯ A k a k {\displaystyle A_{1}^{a_{1}}\cdots A_{k}^{a_{k}}} , which rewrites the coefficients as exponents. Such expressions are called "words", a term borrowed from group theory. (In a particular example


id: aliasing-factorial-experiments-20260505-4
file: data/en.wikipedia.org/wiki/Aliasing_(factorial_experiments)-4.md
category: reference
title: Aliasing (factorial experiments)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Aliasing_(factorial_experiments)
date_saved: 2026-05-05T09:48:49.670316+00:00
instance: kb-cron
parent: aliasing-factorial-experiments-20260505-0
summary:
The use of arithmetic modulo 2 explains why the factor levels in such designs are labeled 0 and 1. === Example 2 === In a 3-level design, factor levels are denoted 0, 1 and 2, and arithmetic is modulo 3. If there are four factors, say A , B , C {\displaystyle A,B,C} and D {\displaystyle D} , the effects group G {\displaystyle \mathbb {G} } will have the relations A 3 = B 3 = C 3 = D 3 = I . {\displaystyle A^{3}=B^{3}=C^{3}=D^{3}=I.} From these it follows, for example, that D 4 = D {\displaystyle D^{4}=D} and D 6 = I {\displaystyle D^{6}=I} . A defining equation such as t 1 + t 2 + t 3 + 2 t 4 = 0 ( mod 3 ) {\displaystyle t_{1}+t_{2}+t_{3}+2t^{4}=0{\pmod {3}}} would produce a regular 1/3-fraction of the 81 (= 3 4 {\displaystyle 3^{4}} ) treatment combinations, and the corresponding defining word would be A B C D 2 {\displaystyle ABCD^{2}} . Since its powers are ( A B C D 2 ) 2 = A 2 B 2 C 2 D {\displaystyle (ABCD^{2})^{2}=A^{2}B^{2}C^{2}D} and ( A B C D 2 ) 3 = I {\displaystyle (ABCD^{2})^{3}=I} ,


id: aliasing-factorial-experiments-20260505-5
file: data/en.wikipedia.org/wiki/Aliasing_(factorial_experiments)-5.md
category: reference
title: Aliasing (factorial experiments)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Aliasing_(factorial_experiments)
date_saved: 2026-05-05T09:48:49.670316+00:00
instance: kb-cron
parent: aliasing-factorial-experiments-20260505-0
summary:
In the 2 3 − 1 {\displaystyle 2^{3-1}} fraction with defining word A B C {\displaystyle ABC} , the maximum resolution is 3 (the length of that word), while the fraction with defining word A B {\displaystyle AB} has maximum resolution 2. The defining words of the 3 4 − 1 {\displaystyle 3^{4-1}} fraction were A B C D 2 {\displaystyle ABCD^{2}} and A 2 B 2 C 2 D {\displaystyle A^{2}B^{2}C^{2}D} , both of length 4, so that the fraction has maximum resolution 4, as indicated. In the 2 5 − 2 {\displaystyle 2^{5-2}} fraction with defining words A B D , A C E {\displaystyle ABD,ACE} and B C D E {\displaystyle BCDE} , the maximum resolution is 3, which is the shortest "wordlength". One could also construct a 2 5 − 2 {\displaystyle 2^{5-2}} fraction from the defining words A B C D {\displaystyle ABCD} and B C D E {\displaystyle BCDE} , but the defining subgroup H {\displaystyle \mathbb {H} } will also include A E {\displaystyle AE} , their product, and so the fraction will only have resolution 2 (the length of A E {\displaystyle AE} ). This is true starting with any two words


id: aliasing-factorial-experiments-20260505-6
file: data/en.wikipedia.org/wiki/Aliasing_(factorial_experiments)-6.md
category: reference
title: Aliasing (factorial experiments)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Aliasing_(factorial_experiments)
date_saved: 2026-05-05T09:48:49.670316+00:00
instance: kb-cron
parent: aliasing-factorial-experiments-20260505-0
summary:
== Partial aliasing == In regular 2 k {\displaystyle 2^{k}} fractions there is no partial aliasing: Each effect is either preserved or completely lost, and effects are either unaliased or completely aliased. The same holds in regular s k {\displaystyle s^{k}} experiments with s > 2 {\displaystyle s>2} if one considers only main effects and components of interaction. However, a limited form of partial aliasing occurs in the latter. For example, in the 3 4 − 1 {\displaystyle 3^{4-1}} design described above the overall A × B × C × D {\displaystyle A\times B\times C\times D} interaction is partly lost since its A B C D 2 {\displaystyle ABCD^{2}} component is completely lost in the fraction while its other components (such as A B 2 C 2 D {\displaystyle AB^{2}C^{2}D} ) are preserved. Similarly, the main effect of A {\displaystyle A} is partly aliased with the B × C × D {\displaystyle B\times C\times D} interaction since A {\displaystyle A} is completely aliased with its B C D 2 {\displaystyle BCD^{2}} component and unaliased with the others. In contrast, partial aliasing is uncontrolled and pervasive in nonregular fractions. In the 12-run Plackett-Burman design described in the previous section, for example,


id: all-pairs-testing-20260505-0
file: data/en.wikipedia.org/wiki/All-pairs_testing-0.md
category: reference
title: All-pairs testing
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/All-pairs_testing
date_saved: 2026-05-05T09:48:50.876127+00:00
instance: kb-cron
parent: all-pairs-testing-20260505-0
summary:
In computer science, all-pairs testing or pairwise testing is a combinatorial method of software testing that, for each pair of input parameters to a system (typically, a software algorithm), tests all possible discrete combinations of those parameters. Using carefully chosen test vectors, this can be done much faster than an exhaustive search of all combinations of all parameters by "parallelizing" the tests of parameter pairs. == Rationale == In most cases, a single input parameter or an interaction between two parameters is what causes a program's bugs. Bugs involving interactions between three or more parameters are both progressively less common and also progressively more expensive to find, such testing has as its limit the testing of all possible inputs. Thus, a combinatorial technique for picking test cases like all-pairs testing is a useful cost-benefit compromise that enables a significant reduction in the number of test cases without drastically compromising functional coverage. More rigorously, if we assume that a test case has N {\displaystyle N} parameters given in a set { P i } = { P 1 , P 2 , . . . , P N } {\displaystyle \{P_{i}\}=\{P_{1},P_{2},...,P_{N}\}} . The range of the parameters are given by R


id: allocation-concealment-20260505-0
file: data/en.wikipedia.org/wiki/Allocation_concealment-0.md
category: reference
title: Allocation concealment
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Allocation_concealment
date_saved: 2026-05-05T09:48:52.131762+00:00
instance: kb-cron
parent: allocation-concealment-20260505-0
summary:
In a randomized experiment, allocation concealment hides the sorting of trial participants into treatment groups so that this knowledge cannot be exploited. Adequate allocation concealment serves to prevent study participants from influencing treatment allocations for subjects. Studies with poor allocation concealment (or none at all) are prone to selection bias. Some standard methods of ensuring allocation concealment include sequentially numbered, opaque, sealed envelopes (SNOSE); sequentially numbered containers; pharmacy controlled randomization; and central randomization. CONSORT guidelines recommend that allocation concealment methods be included in a study's protocol, and that the allocation concealment methods be reported in detail in their publication; however, a 2005 study determined that most clinical trials have unclear allocation concealment in their protocols, in their publications, or both. A 2008 study of 146 meta-analyses concluded that the results of randomized controlled trials with inadequate or unclear allocation concealment tended to be biased toward beneficial effects only if the trials' outcomes were subjective as opposed to objective. Allocation concealment is different from blinding. An allocation concealment method prevents influence on the randomization process, while blinding conceals the outcome of the randomization. However, allocation concealment may also be called "randomization blinding". == Impact == Without the use of allocation concealment,


id: analysis-of-variance-20260505-0
file: data/en.wikipedia.org/wiki/Analysis_of_variance-0.md
category: reference
title: Analysis of variance
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Analysis_of_variance
date_saved: 2026-05-05T09:48:53.349210+00:00
instance: kb-cron
parent: analysis-of-variance-20260505-0
summary:
Analysis of variance (ANOVA) is a family of statistical methods used to compare the means of two or more groups by analyzing variance. Specifically, ANOVA compares the amount of variation between the group means to the amount of variation within each group. If the between-group variation is substantially larger than the within-group variation, it suggests that the group means are likely different. This comparison is done using an F-test. The underlying principle of ANOVA is based on the law of total variance, which states that the total variance in a dataset can be broken down into components attributable to different sources. In the case of ANOVA, these sources are the variation between groups and the variation within groups. ANOVA was developed by the statistician Ronald Fisher. In its simplest form, it provides a statistical test of whether two or more population means are equal, and therefore generalizes the t-test beyond two means. == History == While the analysis of variance reached fruition in the 20th century, antecedents extend centuries into the past according to Stigler. These include hypothesis testing, the partitioning of sums of squares, experimental techniques and the additive model. Laplace was performing hypothesis testing in the 1770s. Around


id: analysis-of-variance-20260505-1
file: data/en.wikipedia.org/wiki/Analysis_of_variance-1.md
category: reference
title: Analysis of variance
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Analysis_of_variance
date_saved: 2026-05-05T09:48:53.349210+00:00
instance: kb-cron
parent: analysis-of-variance-20260505-0
summary:
== Classes of models == There are three classes of models used in the analysis of variance, and these are outlined here. === Fixed-effects models === The fixed-effects model (class I) of analysis of variance applies to situations in which the experimenter applies one or more treatments to the subjects of the experiment to see whether the response variable values change. This allows the experimenter to estimate the ranges of response variable values that the treatment would generate in the population as a whole. === Random-effects models === Random-effects model (class II) is used when the treatments are not fixed. This occurs when the various factor levels are sampled from a larger population. Because the levels themselves are random variables, some assumptions and the method of contrasting the treatments (a multi-variable generalization of simple differences) differ from the fixed-effects model. === Mixed-effects models === A mixed-effects model (class III) contains experimental factors of both fixed and random-effects types, with appropriately different interpretations and analysis for the two types. === Example === Teaching experiments could be performed by a college or university department to find a good introductory textbook, with each text considered a treatment. The fixed-effects model would compare a


id: analysis-of-variance-20260505-2
file: data/en.wikipedia.org/wiki/Analysis_of_variance-2.md
category: reference
title: Analysis of variance
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Analysis_of_variance
date_saved: 2026-05-05T09:48:53.349210+00:00
instance: kb-cron
parent: analysis-of-variance-20260505-0
summary:
The normal-model based ANOVA analysis assumes the independence, normality, and homogeneity of variances of the residuals. The randomization-based analysis assumes only the homogeneity of the variances of the residuals (as a consequence of unit-treatment additivity) and uses the randomization procedure of the experiment. Both these analyses require homoscedasticity, as an assumption for the normal-model analysis and as a consequence of randomization and additivity for the randomization-based analysis. However, studies of processes that change variances rather than means (called dispersion effects) have been successfully conducted using ANOVA. There are no necessary assumptions for ANOVA in its full generality, but the F-test used for ANOVA hypothesis testing has assumptions and practical limitations which are of continuing interest. Problems which do not satisfy the assumptions of ANOVA can often be transformed to satisfy the assumptions. The property of unit-treatment additivity is not invariant under a "change of scale", so statisticians often use transformations to achieve unit-treatment additivity. If the response variable is expected to follow a parametric family of probability distributions, then the statistician may specify (in the protocol for the experiment or observational study) that the responses be transformed to stabilize the variance. Also, a statistician may specify that logarithmic transforms be


id: analysis-of-variance-20260505-3
file: data/en.wikipedia.org/wiki/Analysis_of_variance-3.md
category: reference
title: Analysis of variance
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Analysis_of_variance
date_saved: 2026-05-05T09:48:53.349210+00:00
instance: kb-cron
parent: analysis-of-variance-20260505-0
summary:
The textbook method is to compare the observed value of F with the critical value of F determined from tables. The critical value of F is a function of the degrees of freedom of the numerator and the denominator and the significance level (α). If F ≥ FCritical, the null hypothesis is rejected. The computer method calculates the probability (p-value) of a value of F greater than or equal to the observed value. The null hypothesis is rejected if this probability is less than or equal to the significance level (α). The ANOVA F-test is known to be nearly optimal in the sense of minimizing false negative errors for a fixed rate of false positive errors (i.e. maximizing power for a fixed significance level). For example, to test the hypothesis that various medical treatments have exactly the same effect, the F-test's p-values closely approximate the permutation test's p-values: The approximation is particularly close when the design is balanced. Such permutation tests characterize tests with maximum power against all alternative hypotheses, as observed by Rosenbaum. The ANOVA F-test (of the null-hypothesis that all treatments have exactly the same effect) is recommended as a practical test, because of its robustness against many


id: analysis-of-variance-20260505-4
file: data/en.wikipedia.org/wiki/Analysis_of_variance-4.md
category: reference
title: Analysis of variance
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Analysis_of_variance
date_saved: 2026-05-05T09:48:53.349210+00:00
instance: kb-cron
parent: analysis-of-variance-20260505-0
summary:
==== The number of experimental units ==== In the design of an experiment, the number of experimental units is planned to satisfy the goals of the experiment. Experimentation is often sequential. Early experiments are often designed to provide mean-unbiased estimates of treatment effects and of experimental error. Later experiments are often designed to test a hypothesis that a treatment effect has an important magnitude; in this case, the number of experimental units is chosen so that the experiment is within budget and has adequate power, among other goals. Reporting sample size analysis is generally required in psychology. "Provide information on sample size and the process that led to sample size decisions." The analysis, which is written in the experimental protocol before the experiment is conducted, is examined in grant applications and administrative review boards. Besides the power analysis, there are less formal methods for selecting the number of experimental units. These include graphical methods based on limiting the probability of false negative errors, graphical methods based on an expected variation increase (above the residuals) and methods based on achieving a desired confidence interval. ==== Power analysis ==== Power analysis is often applied in the context of ANOVA in order to


id: analysis-of-variance-20260505-5
file: data/en.wikipedia.org/wiki/Analysis_of_variance-5.md
category: reference
title: Analysis of variance
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Analysis_of_variance
date_saved: 2026-05-05T09:48:53.349210+00:00
instance: kb-cron
parent: analysis-of-variance-20260505-0
summary:
== Cautions == Balanced experiments (those with an equal sample size for each treatment) are relatively easy to interpret; unbalanced experiments offer more complexity. For single-factor (one-way) ANOVA, the adjustment for unbalanced data is easy, but the unbalanced analysis lacks both robustness and power. For more complex designs the lack of balance leads to further complications. "The orthogonality property of main effects and interactions present in balanced data does not carry over to the unbalanced case. This means that the usual analysis of variance techniques do not apply. Consequently, the analysis of unbalanced factorials is much more difficult than that for balanced designs." In the general case, "The analysis of variance can also be applied to unbalanced data, but then the sums of squares, mean squares, and F-ratios will depend on the order in which the sources of variation are considered." ANOVA is (in part) a test of statistical significance. The American Psychological Association (and many other organisations) holds the view that simply reporting statistical significance is insufficient and that reporting confidence bounds is preferred. == Generalizations == ANOVA is considered to be a special case of linear regression which in turn is a special case of the general linear


id: analysis-of-variance-20260505-6
file: data/en.wikipedia.org/wiki/Analysis_of_variance-6.md
category: reference
title: Analysis of variance
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Analysis_of_variance
date_saved: 2026-05-05T09:48:53.349210+00:00
instance: kb-cron
parent: analysis-of-variance-20260505-0
summary:
== References == Anscombe, F. J. (1948). "The Validity of Comparative Experiments". Journal of the Royal Statistical Society. Series A (General). 111 (3): 181–211. doi:10.2307/2984159. JSTOR 2984159. MR 0030181. Bailey, R. A. (2008). Design of Comparative Experiments. Cambridge University Press. ISBN 978-0-521-68357-9. Pre-publication chapters are available on-line. Belle, Gerald van (2008). Statistical rules of thumb (2nd ed.). Hoboken, N.J: Wiley. ISBN 978-0-470-14448-0. Cochran, William G.; Cox, Gertrude M. (1992). Experimental designs (2nd ed.). New York: Wiley. ISBN 978-0-471-54567-5. Cohen, Jacob (1988). Statistical power analysis for the behavior sciences (2nd ed.). Routledge ISBN 978-0-8058-0283-2 Cohen, Jacob (1992). "Statistics a power primer". Psychological Bulletin. 112 (1): 155–159. doi:10.1037/0033-2909.112.1.155. PMID 19565683. S2CID 14411587. Cox, David R. (1958). Planning of experiments. Reprinted as ISBN 978-0-471-57429-3 Cox, David R. (2006). Principles of statistical inference. Cambridge New York: Cambridge University Press. ISBN 978-0-521-68567-2. Freedman, David A.(2005). Statistical Models: Theory and Practice, Cambridge University Press. ISBN 978-0-521-67105-7 Gelman, Andrew (2005). "Analysis of variance? Why it is more important than ever". The Annals of Statistics. 33: 1–53. arXiv:math/0504499. doi:10.1214/009053604000001048. S2CID 13529149. Gelman, Andrew (2008). "Variance, analysis of". The new Palgrave dictionary of economics (2nd ed.). Basingstoke, Hampshire New York: Palgrave Macmillan. ISBN 978-0-333-78676-5. Hinkelmann, Klaus & Kempthorne, Oscar


id: animal-perception-of-magic-20260505-0
file: data/en.wikipedia.org/wiki/Animal_perception_of_magic-0.md
category: reference
title: Animal perception of magic
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Animal_perception_of_magic
date_saved: 2026-05-05T09:48:54.537395+00:00
instance: kb-cron
parent: animal-perception-of-magic-20260505-0
summary:
Researchers study the reactions of animals observing humans performing magic tricks in order to better understand animal cognition. Using these studies, evolutionary psychologists aim to gain insights into the evolution of perception and attention by comparing responses of different species, including humans. == Background == Magic is about violating expectations. It capitalises on specific blind spots in attention and perception. While scientific interest in humans' perception of magic dates back to the late 19th century, when in 1896 Alfred Binet presented his work, this faded quickly, and has only recently, in the early 21st century, been revived. Some researchers have coined terms such as neuromagic or magicology for the study of magic. Other scientists are critical of the new field, saying it is not worthy to stand as a field of its own. Scientists aim to get insight into how the human mind operates. Some animal species are capable of misdirection, an important skill magicians possess to trick humans. For example, chimpanzees have been observed to deliberately look away from an object they desire as to avoid it being noticed by a competitor. Jays and other corvids pretend to store food in various places, trying to obscure the cache's true


id: antecedent-variable-20260505-0
file: data/en.wikipedia.org/wiki/Antecedent_variable-0.md
category: reference
title: Antecedent variable
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Antecedent_variable
date_saved: 2026-05-05T09:48:55.799600+00:00
instance: kb-cron
parent: antecedent-variable-20260505-0
summary:
In statistics and social sciences, an antecedent variable is a variable that cannot help to explain the apparent relationship (or part of the relationship) between other variables that are nominally in a cause and effect relationship. In a regression analysis, an antecedent variable would be one that influences both the independent variable and the dependent variable. == See also == Path analysis (statistics) Latent variable Intervening variable Confounding variable == References == Olobatuyi, M. E. (2006). "Definition of Basic Terms and Concepts". A User's Guide to Path Analysis. University Press of America. pp. 21–52. ISBN 0-7618-3230-0.


id: arrive-guidelines-20260505-0
file: data/en.wikipedia.org/wiki/ARRIVE_guidelines-0.md
category: reference
title: ARRIVE guidelines
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/ARRIVE_guidelines
date_saved: 2026-05-05T09:48:57.054025+00:00
instance: kb-cron
parent: arrive-guidelines-20260505-0
summary:
The ARRIVE guidelines (short for Animals in Research: Reporting In Vivo Experiments) are a set of guidelines for improving experimental design and reporting standards for animal research, drawn up by the National Centre for the Replacement, Refinement and Reduction of Animals in Research. First published in 2010 as a checklist of 20 items, a revision, titled ARRIVE 2.0, was published in 2020 as two checklists of 10 "essential" items and 11 "recommended" items. While the guidelines have been endorsed by over a thousand scientific journals, their adoption and enforcement has remained limited. == Origin == A 2009 review of the quality of experimental design, analysis, and reporting methods of animal research conducted by the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) found that most biomedical journals were providing little or no guidance on how animal research should be analyzed and reported, outside of ethical guidelines for experimental design, such as the Three Rs. Additionally, it found issues with the way animal research is reported, with large proportions of articles not stating a hypothesis or objective of the study, lacking specifics about the characteristics of the animals used, not having used techniques such as randomization


id: association-scheme-20260505-0
file: data/en.wikipedia.org/wiki/Association_scheme-0.md
category: reference
title: Association scheme
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Association_scheme
date_saved: 2026-05-05T09:48:58.210111+00:00
instance: kb-cron
parent: association-scheme-20260505-0
summary:
The theory of association schemes arose in statistics, in the theory of experimental design for the analysis of variance. In mathematics, association schemes belong to both algebra and combinatorics. In algebraic combinatorics, association schemes provide a unified approach to many topics, for example combinatorial designs and the theory of error-correcting codes. In algebra, the theory of association schemes generalizes the character theory of linear representations of groups. == Definition == An n-class association scheme consists of a set X together with a partition S of X × X into n + 1 binary relations, R0, R1, ..., Rn which satisfy: R 0 = { ( x , x ) : x ∈ X } {\displaystyle R_{0}=\{(x,x):x\in X\}} ; it is called the identity relation. Defining R ∗ := { ( x , y ) : ( y , x ) ∈ R } {\displaystyle R^{*}:=\{(x,y):(y,x)\in R\}} , if R in S, then R* in S. If ( x , y ) ∈ R k {\displaystyle (x,y)\in R_{k}} , the number of z ∈ X {\displaystyle z\in X} such that ( x , z ) ∈ R i {\displaystyle (x,z)\in R_{i}} and ( z , y ) ∈ R j {\displaystyle


id: association-scheme-20260505-1
file: data/en.wikipedia.org/wiki/Association_scheme-1.md
category: reference
title: Association scheme
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Association_scheme
date_saved: 2026-05-05T09:48:58.210111+00:00
instance: kb-cron
parent: association-scheme-20260505-0
summary:
== History == The term association scheme is due to (Bose & Shimamoto 1952) but the concept is already inherent in (Bose & Nair 1939). These authors were studying what statisticians have called partially balanced incomplete block designs (PBIBDs). The subject became an object of algebraic interest with the publication of (Bose & Mesner 1959) and the introduction of the Bose–Mesner algebra. The most important contribution to the theory was the thesis of Ph. Delsarte (Delsarte 1973) who recognized and fully used the connections with coding theory and design theory. A generalization called coherent configurations has been studied by D. G. Higman. == Basic facts == p 00 0 = 1 {\displaystyle p_{00}^{0}=1} , i.e., if ( x , y ) ∈ R 0 {\displaystyle (x,y)\in R_{0}} then x = y {\displaystyle x=y} and the only z {\displaystyle z} such that ( x , z ) ∈ R 0 {\displaystyle (x,z)\in R_{0}} is z = x {\displaystyle z=x} . ∑ i = 0 k p i i 0 = | X | {\displaystyle \sum _{i=0}^{k}p_{ii}^{0}=|X|} ; this is because the R i {\displaystyle R_{i}} partition X {\displaystyle X} . == The Bose–Mesner algebra == The adjacency matrices A i {\displaystyle


id: association-scheme-20260505-2
file: data/en.wikipedia.org/wiki/Association_scheme-2.md
category: reference
title: Association scheme
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Association_scheme
date_saved: 2026-05-05T09:48:58.210111+00:00
instance: kb-cron
parent: association-scheme-20260505-0
summary:
== References == Bailey, Rosemary A. (2004), Association Schemes: Designed Experiments, Algebra and Combinatorics, Cambridge University Press, ISBN 978-0-521-82446-0, MR 2047311. (Chapters from preliminary draft are available on-line.) Bannai, Eiichi; Ito, Tatsuro (1984), Algebraic combinatorics I: Association schemes, Menlo Park, CA: Benjamin/Cummings, ISBN 0-8053-0490-8, MR 0882540 Bose, R. C.; Mesner, D. M. (1959), "On linear associative algebras corresponding to association schemes of partially balanced designs", Annals of Mathematical Statistics, 30 (1): 21–38, doi:10.1214/aoms/1177706356, JSTOR 2237117, MR 0102157 Bose, R. C.; Nair, K. R. (1939), "Partially balanced incomplete block designs", Sankhyā, 4 (3): 337–372, JSTOR 40383923 Bose, R. C.; Shimamoto, T. (1952), "Classification and analysis of partially balanced incomplete block designs with two associate classes", Journal of the American Statistical Association, 47 (258): 151–184, doi:10.1080/01621459.1952.10501161 Camion, P. (1998), "18. Codes and Association Schemes: Basic Properties of Association Schemes Relevant to Coding", in Pless, V.S.; Huffman, W.C.; Brualdi, R.A. (eds.), Handbook of Coding Theory, vol. 1, Elsevier, pp. 1441–, ISBN 978-0-444-50088-5 Delsarte, P. (1973), "An Algebraic Approach to the Association Schemes of Coding Theory", Philips Research Reports (Supplement No. 10), OCLC 641852316 Delsarte, P.; Levenshtein, V. I. (1998). "Association schemes and coding theory". IEEE Transactions on Information Theory. 44 (6): 2477–2504. doi:10.1109/18.720545.


id: bayesian-experimental-design-20260505-0
file: data/en.wikipedia.org/wiki/Bayesian_experimental_design-0.md
category: reference
title: Bayesian experimental design
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bayesian_experimental_design
date_saved: 2026-05-05T09:48:59.414261+00:00
instance: kb-cron
parent: bayesian-experimental-design-20260505-0
summary:
Bayesian experimental design provides a general probability-theoretical framework from which other theories on experimental design can be derived. It is based on Bayesian inference to interpret the observations/data acquired during the experiment. This allows accounting for both any prior knowledge on the parameters to be determined as well as uncertainties in observations. The theory of Bayesian experimental design is to a certain extent based on the theory for making optimal decisions under uncertainty. The aim when designing an experiment is to maximize the expected utility of the experiment outcome. The utility is most commonly defined in terms of a measure of the accuracy of the information provided by the experiment (e.g., the Shannon information or the negative of the variance) but may also involve factors such as the financial cost of performing the experiment. What will be the optimal experiment design depends on the particular utility criterion chosen. == Relations to more specialized optimal design theory == === Linear theory === If the model is linear, the prior probability density function (PDF) is homogeneous and observational errors are normally distributed, the theory simplifies to the classical optimal experimental design theory. === Approximate normality === In numerous publications on Bayesian experimental


id: bayesian-experimental-design-20260505-1
file: data/en.wikipedia.org/wiki/Bayesian_experimental_design-1.md
category: reference
title: Bayesian experimental design
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bayesian_experimental_design
date_saved: 2026-05-05T09:48:59.414261+00:00
instance: kb-cron
parent: bayesian-experimental-design-20260505-0
summary:
of which the latter can be evaluated without the need for evaluating individual posterior probability p ( θ ∣ y , ξ ) {\displaystyle p(\theta \mid y,\xi )} for all possible observations y {\displaystyle y} . It is worth noting that the second term on the second equation line will not depend on the design ξ {\displaystyle \xi } , as long as the observational uncertainty doesn't. On the other hand, the integral of p ( θ ) log ⁡ p ( θ ) {\displaystyle p(\theta )\log p(\theta )} in the first form is constant for all ξ {\displaystyle \xi } , so if the goal is to choose the design with the highest utility, the term need not be computed at all. Several authors have considered numerical techniques for evaluating and optimizing this criterion. Note that U ( ξ ) = I ( θ ; y ) , {\displaystyle U(\xi )=I(\theta ;y)\,,} the expected information gain being exactly the mutual information between the parameter θ and the observation y. An example of Bayesian design for linear dynamical model identification are given in . Since I ( θ ; y ) , {\displaystyle I(\theta ;y)\,,} was difficult to calculate, its


id: between-group-design-experiment-20260505-0
file: data/en.wikipedia.org/wiki/Between-group_design_experiment-0.md
category: reference
title: Between-group design experiment
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Between-group_design_experiment
date_saved: 2026-05-05T09:49:00.617094+00:00
instance: kb-cron
parent: between-group-design-experiment-20260505-0
summary:
In the design of experiments, a between-group design is an experiment that has two or more groups of subjects each being tested by a different testing factor simultaneously. This design is usually used in place of, or in some cases in conjunction with, the within-subject design, which applies the same variations of conditions to each subject to observe the reactions. The simplest between-group design occurs with two groups; one is generally regarded as the treatment group, which receives the ‘special’ treatment (that is, it is treated with some variable), and the control group, which receives no variable treatment and is used as a reference (prove that any deviation in results from the treatment group is, indeed, a direct result of the variable). The between-group design is widely used in psychological, economic, and sociological experiments, as well as in several other fields in the natural or social sciences. == Experimental blinds == In order to avoid experimental bias, experimental blinds are usually applied in between-group designs. The most commonly used type is the single blind, which keeps the subjects blind without identifying them as members of the treatment group or the control group. In a single-blind experiment, a placebo is usually


id: blinded-experiment-20260505-0
file: data/en.wikipedia.org/wiki/Blinded_experiment-0.md
category: reference
title: Blinded experiment
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Blinded_experiment
date_saved: 2026-05-05T09:49:01.984530+00:00
instance: kb-cron
parent: blinded-experiment-20260505-0
summary:
In a blind or blinded experiment, information that could influence participants or investigators is withheld until the experiment is completed. Blinding is used to reduce or eliminate potential sources of bias, such as participants’ expectations, the observer-expectancy effect, observer bias, confirmation bias, and other cognitive or procedural influences. Blinding can be applied to different participants in an experiment, including study subjects, researchers, technicians, data analysts, and outcome assessors. When multiple groups are blinded simultaneously (for example, both participants and researchers), the design is referred to as a double-blind study. In some cases, blinding is desirable but impractical or unethical. For example, it is not possible to blind a participant receiving a physical therapy intervention, or a surgeon performing an operative procedure. Well-designed clinical protocols therefore aim to maximize the effectiveness of blinding within ethical and practical constraints. During the course of an experiment, a participant becomes unblinded if they deduce or otherwise obtain information that has been masked to them. For example, a patient who experiences a side effect may correctly guess their treatment, becoming unblinded. Unblinding is common in blinded experiments, particularly in pharmacological trials. In particular, trials on pain medication and antidepressants are poorly blinded. Unblinding that occurs


id: blinded-experiment-20260505-1
file: data/en.wikipedia.org/wiki/Blinded_experiment-1.md
category: reference
title: Blinded experiment
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Blinded_experiment
date_saved: 2026-05-05T09:49:01.984530+00:00
instance: kb-cron
parent: blinded-experiment-20260505-0
summary:
== Unblinding == "Unblinding" occurs in a blinded experiment when information is revealed to someone to whom it has been masked. In clinical studies, unblinding may occur unintentionally when a patient deduces their treatment group. Unblinding that occurs before the conclusion of an experiment is a source of bias. Some degree of premature unblinding is common in blinded experiments. When a blind is imperfect, its success is judged on a spectrum with no blind (or complete failure of blinding) on one end, perfect blinding on the other, and poor or good blinding between. Thus, the common view of studies as blinded or unblinded exemplifies a false dichotomy. The success of blinding is assessed by asking study participants about information that has been masked from them (e.g., whether the participant received the drug or placebo?). In a perfectly blinded experiment, the responses should be consistent with no knowledge of the masked information. However, if unblinding has occurred, the responses will indicate the degree of unblinding. Since unblinding cannot be measured directly, but must be inferred from participants' responses, its measured value will depend on the nature of the questions asked. As a result, it is not possible to objectively measure unblinding.


id: blinded-experiment-20260505-2
file: data/en.wikipedia.org/wiki/Blinded_experiment-2.md
category: reference
title: Blinded experiment
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Blinded_experiment
date_saved: 2026-05-05T09:49:01.984530+00:00
instance: kb-cron
parent: blinded-experiment-20260505-0
summary:
==== Acupuncture ==== While the possibility of blinded trials on acupuncture is controversial, a 2003 review of 47 randomized controlled trials found no fewer than four methods of blinding patients to acupuncture treatment: 1) superficial needling of true acupuncture points, 2) use of acupuncture points which are not indicated for the condition being treated, 3) insertion of needles outside of true acupuncture points, and 4) the use of placebo needles which are designed not to penetrate the skin. The authors concluded that there was "no clear association between the type of sham intervention used and the results of the trials." A 2018 study on acupuncture, which used needles that did not penetrate the skin as a sham treatment, found that 68% of patients and 83% of acupuncturists correctly identified their group allocation. The authors concluded that blinding had failed, but that more advanced placebos may someday enable well-blinded studies in acupuncture. === In physics === It is standard practice in physics to perform blinded data analysis. Once the data analysis is complete, one may unblind the data. A prior agreement to publish the data regardless of the results of the study may be made to prevent publication bias. === In


id: block-design-20260505-0
file: data/en.wikipedia.org/wiki/Block_design-0.md
category: reference
title: Block design
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Block_design
date_saved: 2026-05-05T09:49:03.148970+00:00
instance: kb-cron
parent: block-design-20260505-0
summary:
In combinatorial mathematics, a block design is an incidence structure consisting of a set together with a family of subsets known as blocks, chosen such that number of occurrences of each element satisfies certain conditions making the collection of blocks exhibit symmetry (balance). Block designs have applications in many areas, including experimental design, finite geometry, physical chemistry, software testing, cryptography, and algebraic geometry. Without further specifications the term block design usually refers to a balanced incomplete block design (BIBD), specifically (and also synonymously) a 2-design, which has been the most intensely studied type historically due to its application in the design of experiments. Its generalization is known as a t-design. == Overview == A design is said to be balanced (up to t) if all t-subsets of the original set occur in equally many (i.e., λ) blocks. When t is unspecified, it can usually be assumed to be 2, which means that each pair of elements is found in the same number of blocks and the design is pairwise balanced. For t = 1, each element occurs in the same number of blocks (the replication number, denoted r) and the design is said to be regular. A block design in


id: block-design-20260505-1
file: data/en.wikipedia.org/wiki/Block_design-1.md
category: reference
title: Block design
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Block_design
date_saved: 2026-05-05T09:49:03.148970+00:00
instance: kb-cron
parent: block-design-20260505-0
summary:
obtained from counting for a fixed x the triples (x, y, B) where x and y are distinct points and B is a block that contains them both. This equation for every x also proves that r is constant (independent of x) even without assuming it explicitly, thus proving that the condition that any x in X is contained in r blocks is redundant and r can be computed from the other parameters. The resulting b and r must be integers, which imposes conditions on v, k, and λ. These conditions are not sufficient as, for example, a (43,7,1)-design does not exist. The order of a 2-design is defined to be n = r − λ. The complement of a 2-design is obtained by replacing each block with its complement in the point set X. It is also a 2-design and has parameters v′ = v, b′ = b, r′ = b − r, k′ = v − k, λ′ = λ + b − 2r. A 2-design and its complement have the same order. A fundamental theorem, Fisher's inequality, named after the statistician Ronald Fisher, is that b ≥ v in any 2-design. A rather surprising and not very


id: block-design-20260505-2
file: data/en.wikipedia.org/wiki/Block_design-2.md
category: reference
title: Block design
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Block_design
date_saved: 2026-05-05T09:49:03.148970+00:00
instance: kb-cron
parent: block-design-20260505-0
summary:
Since k = r we can write the order of a projective plane as n = k − 1 and, from the displayed equation above, we obtain v = (n + 1)n + 1 = n2 + n + 1 points in a projective plane of order n. As a projective plane is a symmetric design, we have b = v, meaning that b = n2 + n + 1 also. The number b is the number of lines of the projective plane. There can be no repeated lines since λ = 1, so a projective plane is a simple 2-design in which the number of lines and the number of points are always the same. For a projective plane, k is the number of points on each line and it is equal to n + 1. Similarly, r = n + 1 is the number of lines with which a given point is incident. For n = 2 we get a projective plane of order 2, also called the Fano plane, with v = 4 + 2 + 1 = 7 points and 7 lines. In the Fano plane, each line has n + 1 = 3 points and


id: block-design-20260505-3
file: data/en.wikipedia.org/wiki/Block_design-3.md
category: reference
title: Block design
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Block_design
date_saved: 2026-05-05T09:49:03.148970+00:00
instance: kb-cron
parent: block-design-20260505-0
summary:
== General balanced designs (t-designs) == Given any positive integer t, a t-design B is a class of k-element subsets of X, called blocks, such that every point x in X appears in exactly r blocks, and every t-element subset T appears in exactly λ blocks. The numbers v (the number of elements of X), b (the number of blocks), k, r, λ, and t are the parameters of the design. The design may be called a t-(v,k,λ)-design. Again, these four numbers determine b and r and the four numbers themselves cannot be chosen arbitrarily. The equations are λ i = λ ( v − i t − i ) / ( k − i t − i ) for i = 0 , 1 , … , t , {\displaystyle \lambda _{i}=\lambda \left.{\binom {v-i}{t-i}}\right/{\binom {k-i}{t-i}}{\text{ for }}i=0,1,\ldots ,t,} where λi is the number of blocks that contain any i-element set of points and λt = λ. Note that b = λ 0 = λ ( v t ) / ( k t ) {\displaystyle b=\lambda _{0}=\lambda {v \choose t}/{k \choose t}} and r = λ 1 = λ ( v − 1 t − 1 ) / ( k


id: block-design-20260505-4
file: data/en.wikipedia.org/wiki/Block_design-4.md
category: reference
title: Block design
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Block_design
date_saved: 2026-05-05T09:49:03.148970+00:00
instance: kb-cron
parent: block-design-20260505-0
summary:
R 0 = { ( x , x ) : x ∈ X } {\displaystyle R_{0}=\{(x,x):x\in X\}} and is called the Identity relation. Defining R ∗ := { ( x , y ) ∣ ( y , x ) ∈ R } {\displaystyle R^{*}:=\{(x,y)\mid (y,x)\in R\}} , if R in S, then R* in S If ( x , y ) ∈ R k {\displaystyle (x,y)\in R_{k}} , the number of z ∈ X {\displaystyle z\in X} such that ( x , z ) ∈ R i {\displaystyle (x,z)\in R_{i}} and ( z , y ) ∈ R j {\displaystyle (z,y)\in R_{j}} is a constant p i j k {\displaystyle p_{ij}^{k}} depending on i, j, k but not on the particular choice of x and y. An association scheme is commutative if p i j k = p j i k {\displaystyle p_{ij}^{k}=p_{ji}^{k}} for all i, j and k. Most authors assume this property. A partially balanced incomplete block design with n associate classes (PBIBD(n)) is a block design based on a v-set X with b blocks each of size k and with each element appearing in r blocks, such that there is an association scheme with n classes defined


id: block-design-20260505-5
file: data/en.wikipedia.org/wiki/Block_design-5.md
category: reference
title: Block design
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Block_design
date_saved: 2026-05-05T09:49:03.148970+00:00
instance: kb-cron
parent: block-design-20260505-0
summary:
== References == Aschbacher, Michael (1971). "On collineation groups of symmetric block designs". Journal of Combinatorial Theory. Series A. 11 (3): 272–281. doi:10.1016/0097-3165(71)90054-9. Assmus, E.F.; Key, J.D. (1992), Designs and Their Codes, Cambridge: Cambridge University Press, ISBN 0-521-41361-3 Beth, Thomas; Jungnickel, Dieter; Lenz, Hanfried (1986), Design Theory, Cambridge University Press. 2nd ed. (1999) ISBN 978-0-521-44432-3. Bose, R. C. (1949), "A Note on Fisher's Inequality for Balanced Incomplete Block Designs", Annals of Mathematical Statistics, 20 (4): 619–620, doi:10.1214/aoms/1177729958 Bose, R. C.; Shimamoto, T. (1952), "Classification and analysis of partially balanced incomplete block designs with two associate classes", Journal of the American Statistical Association, 47 (258): 151–184, doi:10.1080/01621459.1952.10501161 Cameron, P. J.; van Lint, J. H. (1991), Designs, Graphs, Codes and their Links, Cambridge University Press, ISBN 0-521-42385-6 Colbourn, Charles J.; Dinitz, Jeffrey H. (2007), Handbook of Combinatorial Designs (2nd ed.), Boca Raton: Chapman & Hall/ CRC, ISBN 978-1-58488-506-1 Fisher, R.A. (1940), "An examination of the different possible solutions of a problem in incomplete blocks", Annals of Eugenics, 10: 52–75, doi:10.1111/j.1469-1809.1940.tb02237.x, hdl:2440/15239 Hall, Marshall Jr. (1986), Combinatorial Theory (2nd ed.), New York: Wiley-Interscience, ISBN 0-471-09138-3 Hughes, D.R.; Piper, E.C. (1985), Design theory, Cambridge: Cambridge University Press, ISBN 0-521-25754-9 Kaski, Petteri; Östergård, Patric (2008).


id: blocking-statistics-20260505-0
file: data/en.wikipedia.org/wiki/Blocking_(statistics)-0.md
category: reference
title: Blocking (statistics)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Blocking_(statistics)
date_saved: 2026-05-05T09:49:20.919707+00:00
instance: kb-cron
parent: blocking-statistics-20260505-0
summary:
In the statistical theory of the design of experiments, blocking is the arranging of experimental units that are similar to one another in groups (blocks) based on one or more variables. These variables are chosen carefully to minimize the effect of their variability on the observed outcomes. There are different ways that blocking can be implemented, resulting in different confounding effects. However, the different methods share the same purpose: to control variability introduced by specific factors that could influence the outcome of an experiment. The roots of blocking originated from the statistician, Ronald Fisher, following his development of ANOVA. == History == The use of blocking in experimental design has an evolving history that spans multiple disciplines. The foundational concepts of blocking date back to the early 20th century with statisticians like Ronald A. Fisher. His work in developing analysis of variance (ANOVA) set the groundwork for grouping experimental units to control for extraneous variables. Blocking evolved over the years, leading to the formalization of randomized block designs and Latin square designs. Today, blocking still plays a pivotal role in experimental design, and in recent years, advancements in statistical software and computational capabilities have allowed researchers to explore more intricate


id: blocking-statistics-20260505-1
file: data/en.wikipedia.org/wiki/Blocking_(statistics)-1.md
category: reference
title: Blocking (statistics)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Blocking_(statistics)
date_saved: 2026-05-05T09:49:20.919707+00:00
instance: kb-cron
parent: blocking-statistics-20260505-0
summary:
In our previous diet pills example, a blocking factor could be the sex of a patient. We could put individuals into one of two blocks (male or female). And within each of the two blocks, we can randomly assign the patients to either the diet pill (treatment) or placebo pill (control). By blocking on sex, this source of variability is controlled, therefore, leading to greater interpretation of how the diet pills affect weight loss. === Definition of blocking factors === A nuisance factor is used as a blocking factor if every level of the primary factor occurs the same number of times with each level of the nuisance factor. The analysis of the experiment will focus on the effect of varying levels of the primary factor within each block of the experiment. === Block a few of the most important nuisance factors === The general rule is: "Block what you can; randomize what you cannot." Blocking is used to remove the effects of a few of the most important nuisance variables. Randomization is then used to reduce the contaminating effects of the remaining nuisance variables. For important nuisance variables, blocking will yield higher significance in the variables of interest than


id: blocking-statistics-20260505-2
file: data/en.wikipedia.org/wiki/Blocking_(statistics)-2.md
category: reference
title: Blocking (statistics)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Blocking_(statistics)
date_saved: 2026-05-05T09:49:20.919707+00:00
instance: kb-cron
parent: blocking-statistics-20260505-0
summary:
Yij is any observation for which X1 = i and X2 = j X1 is the primary factor X2 is the blocking factor μ is the general location parameter (i.e., the mean) Ti is the effect for being in treatment i (of factor X1) Bj is the effect for being in block j (of factor X2) === Estimates === Estimate for μ : Y ¯ {\displaystyle {\overline {Y}}} = the average of all the data Estimate for Ti : Y ¯ i ⋅ − Y ¯ {\displaystyle {\overline {Y}}_{i\cdot }-{\overline {Y}}} with Y ¯ i ⋅ {\displaystyle {\overline {Y}}_{i\cdot }} = average of all Y for which X1 = i. Estimate for Bj : Y ¯ ⋅ j − Y ¯ {\displaystyle {\overline {Y}}_{\cdot j}-{\overline {Y}}} with Y ¯ ⋅ j {\displaystyle {\overline {Y}}_{\cdot j}} = average of all Y for which X2 = j. === Generalizations === Generalized randomized block designs (GRBD) allow tests of block–treatment interaction, and has exactly one blocking factor like the RCBD. Latin squares (and other row–column designs) have two blocking factors that are believed to have no interaction. Latin hypercube sampling Graeco-Latin squares Hyper-Graeco-Latin square designs == See also == Algebraic statistics Block design


id: bose-mesner-algebra-20260505-0
file: data/en.wikipedia.org/wiki/Bose–Mesner_algebra-0.md
category: reference
title: Bose–Mesner algebra
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bose–Mesner_algebra
date_saved: 2026-05-05T09:49:22.162239+00:00
instance: kb-cron
parent: bose-mesner-algebra-20260505-0
summary:
In mathematics, a Bose–Mesner algebra is a special set of matrices which arise from a combinatorial structure known as an association scheme, together with the usual set of rules for combining (forming the products of) those matrices, such that they form an associative algebra, or, more precisely, a unitary commutative algebra. Among these rules are: the result of a product is also within the set of matrices, there is an identity matrix in the set, and taking products is commutative. Bose–Mesner algebras have applications in physics to spin models, and in statistics to the design of experiments. They are named for R. C. Bose and Dale Marsh Mesner. == Definition == Let X be a set of v elements. Consider a partition of the 2-element subsets of X into n non-empty subsets, R1, ..., Rn, such that: given an x ∈ X {\displaystyle x\in X} , the number of y ∈ X {\displaystyle y\in X} such that { x , y } ∈ R i {\displaystyle \{x,y\}\in R_{i}} depends only on i (and not on x). This number will be denoted by vi, and given x , y ∈ X {\displaystyle x,y\in X} with { x , y } ∈


id: bose-mesner-algebra-20260505-1
file: data/en.wikipedia.org/wiki/Bose–Mesner_algebra-1.md
category: reference
title: Bose–Mesner algebra
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bose–Mesner_algebra
date_saved: 2026-05-05T09:49:22.162239+00:00
instance: kb-cron
parent: bose-mesner-algebra-20260505-0
summary:
∑ i = 0 n J i = I . ( 5 ) {\displaystyle \sum _{i=0}^{n}J_{i}=I.\qquad (5)} The Bose–Mesner algebra has two distinguished bases: the basis consisting of the adjacency matrices D i {\displaystyle D_{i}} , and the basis consisting of the irreducible idempotent matrices J k {\displaystyle J_{k}} . By definition, there exist well-defined complex numbers such that D i = ∑ k = 0 n p i ( k ) J k , ( 6 ) {\displaystyle D_{i}=\sum _{k=0}^{n}p_{i}(k)J_{k},\qquad (6)} and | X | J k = ∑ i = 0 n q k ( i ) D i . ( 7 ) {\displaystyle |X|J_{k}=\sum _{i=0}^{n}q_{k}\left(i\right)D_{i}.\qquad (7)} The p-numbers p i ( k ) {\displaystyle p_{i}(k)} , and the q-numbers q k ( i ) {\displaystyle q_{k}(i)} , play a prominent role in the theory. They satisfy well-defined orthogonality relations. The p-numbers are the eigenvalues of the adjacency matrix D i {\displaystyle D_{i}} . == Theorem == The eigenvalues of p i ( k ) {\displaystyle p_{i}(k)} and q k ( i ) {\displaystyle q_{k}(i)} , satisfy the orthogonality conditions: ∑ k = 0 n μ i p i ( k ) p ℓ ( k ) =


