Back to the Main RMSPG page
Back to the RMSPG projects page
ATA: The Allen Telescope Array
to ATA Web site
I. General project/facility description
- Overview of the facility/project
The Allen Telescope Array (ATA) will consist of 350 6.1-meter
dishes arrayed together at the Hat Creek Radio Observatory. The range of
baselines is from about 9.8-meters to about 800-meters. The project is
proceeding in phases delineated by the number of antennas available for use as
an array. The initial phase will yield 32 dishes by Spring of 2005 and is called
the ATA-32. The second phase (ATA-206) will yield 206 dishes expected by
Winter of 2006. The third phase (ATA-350) will yield 350 dishes projected to
be available by the end of 2008. Additional phases yielding more telescopes
are possible in future years.
- Managing institution and organization
The Allen Telescope Array is a joint project between the University
of California Berkeley, Radio Astronomy Laboratory and the SETI
Institute. The array is operated by the Allen Telescope Array
Consortium established in a Memorandum of Understanding between
the Regents of the University of California, Berkeley and the SETI
- Funding source(s)
Funds for the technology development and construction of
the Allen Telescope Array have been raised by the SETI
Institute primarily from a variety of individual and corporate
philanthropic sources. Additional salary and operations
support has been contributed by the state of California,
through its ongoing support of the UC Berkeley Radio Astronomy
Laboratory, an Organized Research Unit at UCB. Additional
funds for acquisition of antennas have come from the USNO.
It is the expectation that NSF funds will become available to
operate the ATA once it comes on line. If the NSF funding
materializes, the ATA will become open for proposals from the
- Construction history and cost
Dollar amounts are in actual year dollars through 2004,
and constant 2004 dollars thereafter. The ATA project was initiated
in 1999 with a MOU signed between UC Berkeley Radio Astronomy
Laboratory and the SETI Institute to cooperate on design and
implementation of an innovative telescope with 104 square
meters of collecting area, suitable for full-time,
simultaneous radio astronomy and SETI observations,
over a very large bandwidth. Significant funding was obtained in 2000,
and a 3 element Production Test Array was installed at Hat Creek Observatory
in Jan 2003. Current plans are for:
The ATA-32 is fully funded and the other phases will proceed as funds
- Spring 2005: ATA-32 begins operation
- Winter 2006: ATA-206 construction complete
- Winter 2007: ATA 350 element array complete.
- Operational history and cost
It is expected that the annual operating costs of the ATA will
be $2M. These funds will be requested from the NSF program for
University Radio Observatories. In addition, the SETI Institute
and UC Berkeley will attempt to raise from other sources an
additional $1M annually for continual upgrades of the digital
IF and back-end processors (the Moore's Law components) to
maximize the capability of the array throughout its life cycle.
II. Technical details
- Specifics of telescope/instrument
The Allen Telescope Array, née the 1 Hectare Telescope, is an array of 350
antennas of 6.1 m diameter with an overall collecting area of 10,000 m2. The
receiver input band covers the whole range of 500 MHz to 11.5 GHz all at once.
This is enabled by dual wide band, low noise input amplifiers (LNAs) connected
to a wide band, dual linearly-polarized, log-periodic feed followed by a dual
fiber optic transmission system of 12 GHz bandwidth. The LNAs are located in a
vacuum dewar cooled by a refrigerator to 50 K to achieve a system temperature
of about 40 K at all wavelengths. The fiber optic system carries the analog
signals from the antenna to the processing laboratory. The antenna reflector
system is an offset Gregorian with a 2.4 m secondary to enable the wide
bandwidth, and there is a metal shroud around the bottom part of the feed to
insure low ground noise and RFI pick-up. The effective areas of the antennas
are approximately frequency independent.
Four bands of 100 MHz each anywhere in the 0.5 - 11.5 GHz range can be
selected for simultaneous processing. Four separate summed beams can be formed
in each band within the primary beam (a total of 16 dual-polarization phased
array beams). Output from each of these beams can be routed to different phased
array backends (PABEs) such as SETI detectors, pulsar machines, or general purpose
spectrometers. Two of the 100 MHz bands can be sent to two 1024 spectral
channel cross-correlators for imaging of the primary field of view. The FX
correlators are configured to output all four stokes parameters. The array is
distributed over a region of about 800 m diameter and provides a resolution of
about one arc minute over the 2.5 degree primary field of view at 1.42 GHz.
That corresponds to about 15,000 independent pixels over the primary field.
The 350 antennas are arranged in such a way that the distributions of baseline
pairs is close to a two dimensional Gaussian. This results in a synthesized
snap-shot beam which has peak near-in sidelobes (over the primary beam) that
are less than one percent.
In addition, the dishes may be used as many independent sub-arrays, where the
number of antennas per sub-array may range from 1 to 350.
The ATA resources available to users are then:
- pointing of the dishes in a sub-array (usually the full 350-dish complement)
- four independent frequency tunings
- four independent phased-array, dual-polarization beams per tuning
- "resourced" phased-array back-ends (i.e. existing PABE's
made available by the provider for use by others, for
example a general-purpose astronomical spectrometer, or
special-purpose back-ends furnished by the proposer).
Note: during most observations, specialized SETI signal
processing equipment will be operating as PABE's on three
or more (out of a total of 16) of the available dual-polarization beams.
- imaging correlator (on two of the independent tunings)
- New capabilities anticipated/planned in next 5-10 years
Future facility. Future upgrades may include:
- The Hat Creek site can accommodate as many as 700 dishes.
Doubling the array collecting area is a possible future option.
- Initial radio astronomy observations will commence with single
correlator on one tuning with 100 MHz of bandwidth. This will
be replicated on a second tuning as soon as funding is available.
Thereafter further generations of correlators will be designed
and built with increased bandwidth per tuning, with a goal of 1
GHz within 10 years. Early PABEs for radio astronomy will be
a pulsar timing machine and a generalized astronomical software
detector in a server cluster.
- Initial SETI signal detectors will provide ~20 MHz of
dual-polarization bandwidth on each of 3 phased-array beams (Prelude system),
evolving into 100 MHz of bandwidth on 4 phased-array beams (SonATA).
Within 10 years, the goal is to have ~1 GHz of bandwidth on each of
eight phased array beams.
III. User profile
- % of "open skies" time
The Telescope Utilization Plan for the ATA anticipates support from
the NSF for annual operating expenses, therefore up to 20% of the
observing time on the ATA-32 and up to 33% of the observing time
on the 350 element ATA will be allocated to external observers.
Formal proposals for observing time will be evaluated by a time
allocation committee, three times per year.
- Institutional affiliations of users
Scientists affiliated with the UC Berkeley Radio Astronomy Lab
and the SETI Institute will have guaranteed-time on the ATA.
- Student access, involvement, usage
The Allen Telescope Array is intended to remain within the
NSF-defined category of a University Radio Observatory rather
than becoming a national observatory facility. This means
that the user will retain a larger degree of involvement in,
and responsibility for, the success of the observing process
(there will be fewer available service-mode observations).
Furthermore, training of the next generation of researchers
will be emphasized. Students will be particularly encouraged
to submit observing proposals, and participate in the ongoing
technical enhancements of the array. Students proposing to
use the ATA as part of their thesis work may also designate
their proposal as a Thesis Proposal, which allows them extra
flexibility and guarantees of array usage.
IV. Science Overview
- Current forefront scientific programs
Future facility: NA
- Major discoveries (through 1999)
Future facility: NA
- Science highlights of last 5 years
Future facility: NA
- Main future science questions to be addressed
- Radio Astronomy:
- All sky survey of HI in galaxies out to z ~ 0.17 (40,000 km/s)
- Study dark matter distribution in galaxies
- Search for dark galaxies
- Observe HI in absorption against AGNs for z < 2
- Study dense ISM and star formation within the Galaxy
- Map dark (molecular) clouds in emission from complex
and long chain molecules [utilizing full receiver
coverage from 0.5 - 11.2 GHz] with good angular resolution
- Measure all 4 Stokes parameters to use the Zeeman effect
in HI and CCS to study the large scale magnetic fields
in the Milky Way and M31, in the regions of field transition,
and in dense molecular clouds
- Map HI at high spatial resolution (~1 arc min) over very large fields
- Characterize the radio transient sky: survey 104 square degrees
at 500 MHz, to 50 µJy or 10 square degrees at 5 GHz to 85 µJy in 12 hours
- Flares from black holes
- 1-100 Gamma Ray Bursters (per 12 hours at 5 GHz)
- Pulsar searches and monitoring
- Pulsars in close binaries
- Old, low duty cycle pulsars
- Large time commitment to pulsar timing program
- Gravitational wave detection: monitoring millisecond pulsars
in the Pulsar Timing Array with 100 nanosecond precision can
sample strain amplitudes of 10-14 and periods of one year.
- The Search for Extraterrestrial Intelligence (SETI) on the ATA:
Based on a plan for signal processing development, and the phased construction
of the ATA, SETI observations will first take advantage of the larger size
of the ATA-32 phased beams to conduct a survey of the inner galactic plane,
and later use the ATA for a sensitive targeted search.
- SETI - survey of inner galactic plane with ATA-32 and
Prelude signal processing equipment (2005 Q1 - 2006 Q4)
- +/-1° of galactic latitude, from galactic
longitude 0° to 90°.
- 2-beams scanning in constant galactic latitude, 28 MHz bandwidth per beam
- near-real-time searches for CW and pulsed signals
- 10 hours per day (exclusive control of array, not commensal modality)
- 80,000 pointings at 10 seconds per point
- Detection limit ~5 × 10-24 Wm-2
(3 x 1018 W EIRP at 25,000 ly)
- SETI - targeted search of between 105 and 106
solar-type stars using SonATA signal processing equipment (2007 Q1 - 2016 Q4).
- 1 - 10 GHz frequency range
- 300 seconds per beam per frequency × 2 or 3 lookbacks
- Initial observations will use 4 phased array beams with 100 MHz each
- Evolve to using 8 phased array beams with perhaps 1 GHz of bandwidth each.
- Near-real-time searches for CW and pulsed signals,
expanding over time to include more complex and noise-like classes of signal
- Near-continuous commensal observations
- Detection limit ~1 × 10-25 Wm-2
(1014 W EIRP at 1000 ly)
- Synergies with other major forefront facilities
- Down link for bistatic radar from Arecibo or Goldstone.
- VLBI station in conjunction with VLBA, HSA, etc.
- Rapid response to GRB or other transient phenomena (no feed change required
0.5 - 11.2 GHz, fully steerable horion to horizon with slew rate < 4°/sec,
- Unique contributions
- 22 to 1 bandwidth, simultaneous access to 0.5-11.2 GHz
- fast survey speed (wide primary field of view and 15,000 pixel
imaging resolution with 1024 channels per pixel from correlator),
- excellent transient detector,
- simultaneous ability to image primary field of view and position up
to 16 dual-polarization phased array beams,
- ability to form wide bandwidth and wide angle nulls anywhere on sky,
- excellent psf for correlator and phased beam with < 1% near-in sidelobes,
- excellent snapshot images (61075 baselines),
- ability to image below 1 GHz (HI to z=2),
- supports multiple scientific users simultaneously.
V. Education/Outreach activities
- Visitor facility
Hat Creek Observatory currently hosts nearly 1000 visitors
each year, even though it does not yet have a formal visitor
center. These visitors are primarily school classes
during the academic year, and families on vacation during
the summer. With the start of construction of the ATA, there is
increasing public interest in the facility and plans
have been drawn up to convert an old laboratory building
close to the site access road into a temporary visitor
and information center. The EP/O office at the SETI
Institute has begun discussions with the Turtle Bay
Exploration Park located in Redding, CA about one hour from the site.
During the construction of the ATA, exhibits will be developed
for use at Turtle Bay and a formal program of guided tours to
the site will be established. In conjunction with the staff at
Turtle Bay, a formal proposal will be developed for submission
to the McConnell Foundation (whose philanthropy is targeted at
Shasta and Lassen counties in Northern CA) and the NSF for the
construction and operation of an ATA visitor center that
involves people of all ages and abilities with the observatory
and its scientific programs, without exposing the site to the
interference produced by people with digital electronics and
- Student programs
Following the very successful practice of the BIMA facility
at the Hat Creek Radio Observatory, the ATA will continue to
host an intensive, week-long, residential Summer School at the
array for interested students, post-docs and researchers during
the summer months (historically in June). This Summer School
will train new users about the use of interferometers in general,
and the ATA in particular. It will involve actual observations
taken and analyzed by each participant during the course of the
Summer School. Staff from the University of California, the
SETI Institute and other qualified staff will provide the
presentations and oversight to effect this Summer School.
In partial compensation for this training, participants will
be requested to return to Hat Creek for one week during the
next year to serve as an observer in residence, whose general
duties are to maximize the scientific output of the scheduled
observations. Opportunities for participation in the Summer
School will be widely advertised, and will be open to all
applicants subject only to restrictions on the number of
individuals that can be accommodated by the on-site residence facilities.
VI. Documentation/website URLs
- URL of facility website
- URL of EPO website
- URL(s) of any brief overviews of project/facility
- URL(s) of miscellaneous documentation
Note: this is not a public website.
This page created and maintained for the RMSPG by
Last modified: Tue Feb 8 08:44:49 EST 2005 after review by Wm. J. Welch.