Murchison Widefield Array (MWA) : Design and Status Divya Oberoi, Lenoid Benkevitch MIT Haystack Observatory doberoi, On behalf of the MWA Project

Partner Institutions and Sponsors

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

The design approach Collaborators Logistics Politics

RFI Ionosphere Wide FoV Calibration & Mapping

RFI Ionosphere Wide FoV Calibration & Mapping Baseline Length

RFI Ionosphere Wide FoV Calibration & Mapping

RFI Ionosphere Wide FoV Calibration & Mapping Shire of Murchison. Pop: 199 Area: 41,173 km 2 (NL: ~41,500 km 2 )‏ (UK: ~244,820 km 2 )‏  Humans ~ 10 5 lower than MA, UK, NL

RFI Ionosphere Wide FoV Calibration & Mapping

Array Configuration

u-v coverage Monochromatic snapshot Zenith pointing

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

Murchison Widefield Array Frequency range MHz Number of receptors 8192 dual polarization dipoles Number of tiles 512 Collecting area ~8000 m 2 (at 200 MHz) Field of View ~15°-50° (1000 deg 2 at 200 MHz) Configuration Core array ~1.5 km diameter (95%, 3.4’) + extended array ~3 km diameter (5%, 1.7’) Bandwidth 220 MHz (Sampled); MHz (Processed) # Spectral channels 1024 (3072) Temporal resolution 8 s (0.5 s) Polarization Full Stokes Point source sensitivity 20mJy in 1 s (30.72 MHz, 200 MHz) 0.34mJy in 1 hr Multi-beam capability 32, single polarization Number of baselines (VLA: 351, GMRT: 435, ATA: 861)

Choice of Science Objectives

Key Features of Interest Magnetic field measurements in the corona and heliosphere via Faraday rotation observations – 1 source every 6-9 deg 2 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

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

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

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

Best image so far Pictor A, MHz  = 330 mJy Christopher Williams, MIT 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+

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  MHz – A strong possibility of an interim 128T array, while we build out to 512T.

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…

RFI Ionosphere Wide FoV Calibration & Mapping Baseline Length

Array Configuration

Array Coplanarity Peak-to-peak variation ~5 m (excluding outliers) 0.5 m contours Accuracy of topgographic data 0.5m

Choice of Science Objectives

First Light Images from MWA prototype Pictor A, 159 MHz, 1.28 MHz (10 kHz), 5 min (1 s), 24 Elements R. Wayth, CfA 10 

ObservationsSimulated map R. Wayth, CfA Pictor A, 159 MHz, 1.28 MHz (10 kHz), 5 min (1 s), 24 Elements First Light Images from MWA prototype 10 