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Partner Institutions and Sponsors

Murchison Widefield Array (MWA ) : Design and Status Divya Oberoi , Lenoid Benkevitch MIT Haystack Observatory doberoi, benkev@haystack.mit.edu On behalf of the MWA Project. Partner Institutions and Sponsors. What is the MWA?. A low-frequency imaging array 80 – 300 MHz

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Partner Institutions and Sponsors

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  1. Murchison Widefield Array (MWA) : Design and StatusDivyaOberoi, LenoidBenkevitchMIT Haystack Observatory doberoi, benkev@haystack.mit.eduOn behalf of the MWA Project

  2. Partner Institutions and Sponsors

  3. What is the MWA? • A low-frequency imaging array • 80 – 300 MHz • Wide Field of View (FoV) • Array elements – arrays of dipoles

  4. The design approach Collaborators Science Objectives Funding Opportunities Ionosphere Politics Instrument performance requirements Instrument design Wide FoVCalib. & Mapping Technical Feasibility RFI Logistics Economic Feasibility

  5. Relevant length scales • Size of the array aperture (A) • Scale size of ionospheric structure (S) • Field of View (V) Ionosphere RFI Wide FoV Calibration & Mapping

  6. Relevant length scales • Size of the array aperture (A) • Scale size of ionospheric structure (S) • Field of View (V) • Frequency of observation • 2 dependence Ionosphere RFI Baseline Length Wide FoV Calibration & Mapping

  7. MWA Approach • Do the easier problem first • Go to higher end of the frequency range where one can still build up collecting area from inexpensive dipoles • Compact footprint (A << S) • Mid-latitude site – less dynamic ionosphere • Build up some experience  the next step Ionosphere RFI Wide FoV Calibration & Mapping

  8. MWA Approach Intrinsically RFI quiet site Shire of Murchison. Pop: 199 Area: 41,173 km2 (NL: ~41,500 km2)‏ (UK: ~244,820 km2)‏ Ionosphere RFI  Humans ~105 lower than MA, UK, NL Wide FoV Calibration & Mapping

  9. MWA Approach • Sufficient sensitivity to have a reasonable snapshot Calibrator grid density • Good monochromatic snapshot imaging capability • All sky imaging - visibilities maintain coherence from horizon to horizon • Simple design - no moving parts • Highly redundant array Ionosphere RFI Wide FoV Calibration & Mapping

  10. Array Configuration

  11. u-v coverage Monochromatic snapshot Zenith pointing

  12. Point Spread Function 3-4% ~0.3% -10.2%

  13. Murchison Widefield Array

  14. Choice of Science Objectives Monochromatic snapshot imaging Epoch of Reionization PSF Quality • Solar Heliospheric and Ionospsheric (SHI) Science • Solar Imaging • Interplanetary Scintillation • Heliospheric Faraday rotation • Ionospheric studies • Transients • Imaging • Light curve analysis Wide FoV Sensitivity Simple design 80-300 MHz

  15. Key Features of Interest • Magnetic field measurements in the corona and heliosphere via Faraday rotation observations • 1 source every 6-9 deg2 • Velocity, turbulence characteristics etc. via IPS • 32 independent beams and wide fields of view • Location and evolution of shocks via imaging of Type II bursts • Very good monochromatic snap-shot imaging capabilities • Sufficient time and spectral resolution

  16. 32 Tile Prototype • Motivation • Engineering test bed • End to end signal/data path and system performance testing • Training data sets for calibration system • Learning to operate in the site conditions • Early Science

  17. Broadband spectrum Defense satellite network FM Band Orbcomm satellites A. Roshi, RRI

  18. First Light Images from MWA prototype Puppis A, 159 MHz, 1.28 MHz (10 kHz), 24 elements R. Wayth, CfA/Curtin Uni.

  19. Best image so far Pictor A, 158.7 MHz • 7, 5min scans, spread over 6 hours • 1.28 MHz • 27 tiles • Crosses mark the location of sources of with flux > 2Jy (1420 MHz) • Dynamic Range 1000+  = 330 mJy Christopher Williams, MIT

  20. Status and Schedule • Analog hardware for 32T system in place • Digital hardware (correlator) deployment - June 09 • 32T performance testing - 4Q 2009 • End of build-out phase for the final system – 3-4Q 2010 • Science capabilities will slowly grow starting now • Remote operations started • Hardware correlator 30.72 MHz • A strong possibility of an interim 128T array, while we build out to 512T.

  21. Summary • MWA - optimized for calibration and imaging challenges at low frequencies • Needs of the key science applications and the instrument’s capabilities are very well matched • Data flow from the prototype array has commenced • Busy schedule and exciting times ahead • Stay tuned…

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