Fact Sheet

About the Allen Telescope Array (ATA)

The ATA is a radio interferometer that is dedicated to cutting-edge astronomical research and a simultaneous search for signals of intelligent, extraterrestrial origin. It is at the Hat Creek Radio Observatory, 290 miles northeast of San Francisco, California and will be composed of 350 antennas at completion. The ATA advances the field of radio astronomy.

Gathering DATA

The ATA is a new, innovative research telescope with unique capabilities, including:

  • Collecting and analyzing an unprecedented, large amount of data (4.5 octaves of frequency)
  • Scanning a much larger area of the sky with a wider view of focus than existing telescopes
  • The ATA can be easily upgraded as computer and telecommunications technology improve
  • An innovative use of many inexpensive, small radio dishes linked together creating the equivalent of a very large telescope
  • Conducting radio astronomical research and SETI research simultaneously

For Astronomers:  download The ATA performance PDF


For scientists at the SETI Institute, the ATA offers not only its inherent speed, but also the simple advantage of being usable 24/7 for research and data collection.  For radio astronomy, the ATA can scan more of the sky very rapidly and create precise measurements of distant celestial objects.

Technology and Scale

The ATA takes advantage of the evolution of electronics and technology:

  • Radio telescopes of the past either were giant, single-dish antennas, or consisted of a few dozen large antennas linked together.  Thanks to the plummeting price of electronics, a collection of small antennas now costs less than a single, large dish.  The ATA utilizes this new circumstance, and the result is a “radio camera” able to make radio images in a fraction of the time of other instruments. 
  • The capabilities of the ATA versus traditional radio telescopes can be compared the capabilities of a Mathew Brady tripod-mounted camera of the Civil War era, taken with a long, slow exposure, versus a digital point-and-shoot camera of today.
  • The ATA can conduct research over a very wide portion of the radio spectrum. Whether being used for astronomy or extraterrestrial intelligence, four separately tunable radio frequency bands can be examined simultaneously. Changing frequencies on the ATA is just a matter tapping a key on a computer to retune, without mechanically having to change receivers.


  • 2001 – Paul G. Allen Family Foundation provides $11.5 million in funding to support infrastructure building costs for the Allen Telescope Array project
  • 2001-2004 – Research and development phase for the Allen Telescope Array leading to the installation of the 3-dish Production Test Array at Hat Creek
  • 2003 – Paul G. Allen Family Foundation provides additional $13.5 million to build the initial phase of the ATA project
  • 2004 – A three-tier construction plan for telescope is unveiled
  • 2005 – Construction begins
  • 2006 – The first 30 antennas are in place and installed at Hat Creek Radio Observatory
  • 2007 – First phase of project complete with 42 working antennas
  • 2009 - Routine observing begins
  • 2011 - Hibernation due to lack of operations funding
  • 2011 - SETI searches of Kepler Worlds begin
  • 2012 - SRI International becomes operator of the Hat Creek Radio Observatory, routine observations continue

Key Science Goals

  • Determine the neutral hydrogen (HI) content of galaxies over three-quarters of the sky, to measure how much intergalactic gas external galaxies are accreting; to search for dark, starless galaxies; to lay the foundation for SKA dark energy detection
  • Classify 250,000 extragalactic radio sources as active galactic nuclei or starburst galaxies, to probe and quantify star formation in the local universe; to identify high red shift objects; to probe large-scale structure in the universe; to identify gravitational lens candidates for dark matter and dark energy detection
  • Measure the magnetic fields in the Milky Way and other Local Group Galaxies to probe the role of magnetic fields in star formation and galaxy formation
  • Detect the gravity-wave background from coalescing massive black holes through pulsar timing
  • Measure molecular cloud and star formation properties using new molecular tracers to map the star formation conditions on the scale of entire Giant Molecular Clouds and to determine the distribution of heavy elements in the Milky Way
  • Explore the transient sky, to probe accretion onto black holes, to discover orphan gamma-ray burst afterglow, to discover new and unknown transient phenomena
  • Survey 1,000,000 stars for non-natural extraterrestrial signals with enough sensitivity to detect the equivalent power of the Arecibo radar out to 1000 light-years within the frequency range of 1 to 10 GHz
  • Survey the 4×1010 billion stars of the inner Galactic Plane in the “water hole” frequency range from 1420 MHz to 1720 MHz for very powerful, non-natural transmitters
  • Explore the thousands of exoplanet systems that have been discovered by the Kepler Spacecraft and groundbased observatories from 1 to 10 GHz
  • SRI International has replaced UC Berkeley as the operator of the Allen Telescope Array under contract with the USAF (View official AFSPC press release here)