Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.naic.edu/~astro/chicago2/talks/Bower-ATA_SKA_Development_Facility.pdf Äàòà èçìåíåíèÿ: Tue Aug 22 17:44:33 2006 Äàòà èíäåêñèðîâàíèÿ: Sun Dec 23 00:55:51 2007 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: m 103

Allen Telescope Array Status --ATA SKA Development Facility

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Geoffrey C. Bower UC Berkeley

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Allen Telescope Array
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Large N design ­ 350 x 6.1m antennas ­ Sensitivity of the VLA ­ Unprecedented imaging capabilities Continuous frequency coverage ­ 0.5 to 11.2 GHz Wide field of view ­ 3 degrees at 1 GHz ­ Excellent survey instrument: 17x FOV of VLA

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Compact Configuration
­ 1 arcmin at 1.4 GHz (350), 1 arcmin at 5 GHz (42) Simultaneous observing with multiple backends ­ Correlator: 2 x 100 MHz x full Stokes x 1024 channels ­ Phased array beams: 32 indepent at 4 frequencies Joint project of UC Berkeley/SETI Inst. Privately funded construction ($26M)
­ ­ NSF support for correlator & operations ($2.2M) USNO support for construction ($3M)

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ATA Science
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­ GC survey: 20 sq. deg, 1.4-1.7 GHz, 6 months ­ 106 stars over 1-10 GHz
· Arecibo radar detectable at 300 pc

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­ Simultaneous with correlator

Extragalactic HI survey
­ Neutral gas SDSS equivalent ­ L* at z=0.1 over the entire sky

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­ Transients ­ All sky surveys

LGS 3

Galactic magnetic fields, HI, longchain molecules Pulsars Radio continuum science

Robishaw, Simon & Blitz 2002

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The Antenna
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· 6.1-m offset Gregorian · Low diffractive spillover ~1% at all elevations · Surface rms ~ 1mm · Works to 25 GHz · Going to 45 GHz will double cost of mounts and mirrors

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ATA-42 Operational Soon
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4 deg/sec in azimuth, 2 deg/sec in elevation Movie 3x real time

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Large angle beam pattern
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Excellent Pointing
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5e GPS Pointing 1.5 GHz
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1.2 rms

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Radio Pointing

Optical Pointing


ATA Log-Periodic Feed
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LNAs from Weinreb & Wadefalk
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~35 K

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~10 K


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Correlator


Simultaneous Single Dish Spectrum
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M31 in a Single Pointing
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ATA SKA Development Facility
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· Use ATA infrastructure for SKA development · Concept originally proposed in TDP · Community opportunity for development · Available now

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ATA SKA Dev. Facility Activities
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· Feed development & testing
­ High frequency extension of logperiodic feed ­ Test other broadband feed designs ­ Feed manufacturing, component design

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ATA SKA Dev. Facility Activities
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·Calibration & Imaging
­Form multiple phased array beams ­Test stability, calibration, interference rejection capabilities of phased array signals for SKA station use ­Simultaneous in-beam calibrator observations for precision VLBI astrometry and faint source detection ­Wide-field imaging ­Automated imaging algorithms & hardware

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ATA SKA Dev. Facility Activities
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·Interference mitigation
­Nulling ­Adaptive cancelling ­Post-correlation

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ATA SKA Dev. Facility Activities
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·Digital backend devices
­Put your hardware on one or more phased array beams ­Broadband devices, large-N devices

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The ATA is a Community Resource
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· ATA-42 Coming Soon
­ NSF URO 30% observing time for the community ­ Opportunities to collaborate sooner on science

· LNSD demonstrator · SKA Development Facility
­ Technical development necessary to meet SKA goals ­ Developing collaboration with NRAO on technology ­ Community opportunity towards developing increased cm wavelength capabilities

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