---
title: "Allen Telescope Array"
chunk: 3/4
source: "https://en.wikipedia.org/wiki/Allen_Telescope_Array"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T13:15:32.906338+00:00"
instance: "kb-cron"
---

== History ==
Since its inception, the ATA has been a development tool for astronomical interferometer technology (specifically, for the Square Kilometer Array).
The ATA was originally planned to be constructed in four stages, ATA-42, ATA-98, ATA-206 and ATA-350, each number representing the number of dishes in the array at a given time (See Table 1). The ATA is planned to comprise 350 dishes with a diameter of 6 m each.
Regular operations with 42 dishes started on 11 October 2007. Funding for building additional antennas is currently being sought by the SETI Institute from various sources, including the United States Navy, Defense Advanced Research Projects Agency (DARPA), National Science Foundation (NSF) and private donors.
Simultaneous astronomical and SETI observations are performed with two 32-input dual polarization imaging correlators. Numerous articles reporting conventional radio astronomy observations have been published.
Three phased array beamformers utilizing the Berkeley Emulation Engine 2 (BEE2) were deployed in June 2007 and have been integrated into the system to allow for simultaneous astronomical and SETI observations. As of April 2008, the first pulsar observations were conducted using the beamformer and a purpose-built pulsar spectrometer.
The workhorse SETI search system (SETI on ATA or SonATA) performs fully automated SETI observations. SonATA follows up on detected signals in real time and continues to track them until 1) the signal is shown to have been generated on Earth or rarely, 2) the source sets, which triggers follow up the next day. As of 2016, more than two hundred million signals have been followed up and classified  using the ATA. Not one of these signals had all the characteristics expected for an ETI signal. The results of SETI Institute's observations are published in a number of papers.
In April 2011, the ATA was put into hibernation owing to funding shortfalls, meaning that it was no longer available for use.  Operation of the ATA resumed on 5 December 2011. Efforts are now led by Andrew Siemion.

=== Status ===
In 2012, the ATA was funded by a $3.6 million philanthropic donation by Franklin Antonio, cofounder and Chief Scientist of Qualcomm Incorporated. This gift supports upgrades of all the receivers on the ATA dishes to have dramatically greater sensitivity (2 − 10× from 1–8 GHz) than before and support sensitive observations over a wider frequency range, from 1–15 GHz, when initially the radio frequency electronics went to only 11 GHz. By July 2016, the first ten of these receivers had been installed and proven. Full installation on all 42 antennas is planned as of June 2017.
In November 2015, the ATA studied the anomalous star KIC 8462852, and in autumn 2017 the Allen Telescope Array examined the interstellar asteroid  ʻOumuamua for signs of technology, but detected no unusual radio emissions.

== Key science goals ==

The science goals listed below represent the most important projects to be conducted with the ATA. Each of these goals is associated with one of the four stages of development mentioned earlier. (See Table 1). Also listed is some of the science that it is hoped each will produce.

Determine the hydrogen line (HI) content of galaxies out to z ~ 0.2 over 3π steradians, in order to measure how much intergalactic gas external galaxies are accreting; to search for dark, starless galaxies; to lay the foundation for dark energy detection by the Square Kilometer Array.
Classify 250,000 extra-galactic radio sources as active galactic nuclei or starburst galaxies, in order to probe and quantify star formation in the Local Universe; to identify high redshift objects; to probe large-scale structure in the Universe; to identify gravitational lens candidates for dark matter and dark energy detection.
Explore the transient sky, in order to probe accretion onto black holes; to find orphan gamma ray burst afterglows; to discover new and unknown transient phenomena.
Survey 1,000,000 stars for SETI-related emission with enough sensitivity to detect an Arecibo radar out to 300 parsecs within the range of 1–10 GHz.
Survey the 4×1010 stars of the inner galactic plane from 1.42–1.72 GHz for very powerful transmitters.
Measure the magnetic fields in the Milky Way and other Local Group galaxies, in order to probe the role of magnetic fields in star formation and galaxy formation and evolution.
Detect the gravitational wave background from massive black holes through pulsar timing.
Measure molecular cloud and star formation properties using new molecular tracers, in order to map star formation conditions on the scale of entire giant molecular clouds (GMCs); to determine the metallicity gradient of the Milky Way.

== Opportunistic science ==
Since construction of the array began, a few science goals not specifically drawn up for it have been suggested.
For example, the Allen Telescope Array has offered to provide the mooncast data downlink for any contestants in the Google Lunar X Prize. This is practical, since the array, with no modifications, covers the main space communications bands (S-band and X-band). A telemetry decoder would be the only needed addition.
Also, the ATA was mentioned as a candidate for searching for a new type of radio transient. It is an excellent choice for this owing to its large field of view and wide instantaneous bandwidth. Following this suggestion, Andrew Siemion and an international team of astronomers and engineers developed an instrument called "Fly's Eye" that allowed the ATA to search for bright radio transients, and observations were carried out between February and April 2008.

== Instruments ==