the murchison widefield array: an ska precursor

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The Murchison Widefield Array: an SKA Precursor. Shep Doeleman - MIT Haystack For the MWA Project. A wide-field, low-frequency imaging array Optimized for wide FOV, high survey speed Frequency range 80-300 MHz: Sample RF Three key science goals Epoch of Reionization - PowerPoint PPT Presentation

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  • The Murchison Widefield Array:an SKA PrecursorShep Doeleman - MIT HaystackFor the MWA Project

  • What is the MWA?A wide-field, low-frequency imaging array Optimized for wide FOV, high survey speedFrequency range 80-300 MHz: Sample RF Three key science goals Epoch of Reionization Solar, Heliospheric and Ionospheric Radio Transients Designed to exploit RFI-quiet site in Western Australia

  • The PartnershipMassachusetts Institute of TechnologyHaystack Observatory (Project Office)Kavli InstituteHarvard SAOCSIRO (via synergy with ASKAP)UMelbourne, Curtin, ANU (founding partners)USydney, UTasmania, UWA, and others, ...Raman Research Institute, IndiaGovernment of WA*

  • Murchison

  • RFI Environment

  • Physical Layout

  • Production Dual-Pol Antenna*

  • Tentative ConfigurationAperture Plane UV Plane

  • Point Spread Function*

  • 1024sigA/DCoarse PFBSelect 30.72MHz 20 Tflops192 fibers over 1-3km32 single pol524,288 sig pairs18 Tera CMACs10kHz resolution0.5 sec accumulate160Gb/s80-300MHz2-10 TflopNo FringeStopping

  • Ionospheric Calibration

  • MWA as SKA PrecursorLarge NArray configurationLarge data transport flowLarge multiplier for all processingCorrelator architectureCalibration algorithms: real timeCannot store raw dataBroad Science CaseWide Field by design: transientsNew analysis algorithms: EOR statisticsLinks with solar, space weather communityRemote SiteInternational Project

  • ScheduleSeptember 08 to March 09 32-tile system: as of yesterday 16 tiles fully functional (w/ bf and rx).Progressive testing of production hardware systems Milestone for funds release, June 09 April 09 to December 09 Buildout to ~256 tile system In-depth testing, refinement of algorithms January 2010 to June 2010 Complete buildout to 512 tiles Initiate key science investigations 2010 - 2012 Refinement and incremental expansion 2013 and beyond Possible major expansion

  • Murchison Widefield Array: Design*

  • Murchison Widefield Array: Specs

    Frequency range80-300 MHzNumber of receptors8192 dual polarization dipolesNumber of tiles512Collecting area~8000 m2 (at 200 MHz)Field of View~15-50 (1000 deg2 at 200 MHz)ConfigurationCore array ~1.5 km diameter (95%, 3.4) +extended array ~3 km diameter (5%, 1.7)Bandwidth220 MHz (Sampled); 31 MHz (Processed)# Spectral channels1024Temporal resolution8 secPolarizationFull StokesPoint source sensitivity20mJy in 1 sec (32 MHz, 200 MHz)0.34mJy in 1 hrMulti-beam capability32, single polarizationNumber of baselines130,816 (VLA: 351, GMRT: 435, ATA: 861 )

  • Where and Why*Next Generation Heliospheric Imager Workshop, NSO, SunspotrHumans ~ 0.003 km2

    Next Generation Heliospheric Imager Workshop, NSO, Sunspot

  • Murchison Widefield Array**Next Generation Heliospheric Imager Workshop, NSO, Sunspot

    Next Generation Heliospheric Imager Workshop, NSO, Sunspot

  • 32 Tile system: Specs

    32 tiles, 4 nodest = 50 ms Aeff = 550 m2 (~6% of MWA)0 ~15 @ 200 MHzBandwidth = 31 MHz496 physical baselines = 10 kHzMax data rate ~12.7 Mvis/s (1TByte in ~2h45min)

  • MWA Current StatusA team is currently on site8 element interferometer to be set up by the end of April 0832 element interferometer by July 08

    Major construction phase to begin shortly after that*Next Generation Heliospheric Imager Workshop, NSO, Sunspot

    Next Generation Heliospheric Imager Workshop, NSO, Sunspot

  • Murchison Widefield ArrayPrimary Science ObjectivesEpoch of ReionizationSolar, Heliospheric and Ionospheric ScienceTransientsCollaborating InstitutionsMIT Haystack, MKI, CfA (NSF Ast and Atm, AFOSR)7 Australian InstitutionsRaman Research Institute, India~20 MUSD

    *Next Generation Heliospheric Imager Workshop, NSO, Sunspot

    Next Generation Heliospheric Imager Workshop, NSO, Sunspot

  • MWA Science GoalsEpoch of ReionizationPower spectrumStrmgren spheresSolar/Heliospheric/IonosphericFaraday rotation, B-field of CMEsInterplanetary ScintillationSolar burst imagingTransientsDeep blind surveyLight curves (field and targeted)Synoptic surveysOtherPulsarsISM surveyRecombination linesEtc.

  • The Epoch of Re-ionizationAfter ~300,000 years electrons and protons combine to form hydrogen

    After ~1 billion years stars and quasars ignite, radiation splits hydrogen into protons and electrons.

    In between are the Dark Ages

  • Why is low freq radio astronomy suddenly so hot?Huge advances in digital hardware affordability of capable instrumentationEnormous increase in affordability of computing (considering a few Tflops machine for MWA)Considerable and continuing effort in development of calibration algorithms and techniques*Next Generation Heliospheric Imager Workshop, NSO, Sunspot

    Next Generation Heliospheric Imager Workshop, NSO, Sunspot

  • Key design considerationsHigh dynamic range imagingCalibrability

    *Next Generation Heliospheric Imager Workshop, NSO, Sunspot Large number of interferometer elements Full cross-correlation architecture Full field-of-view imaging

    Compact array foot print

    Next Generation Heliospheric Imager Workshop, NSO, Sunspot

  • MWA Data/Computation Rates Sampler output1024 x 660 MHz x 8 bits = 5.3 Terabits/sec Coarse Polyphase filterbank Performed on full data rate in real time Processing done by 512 Xilinx SX-35 FPGAs Of order 20 Tflops, massively parallel Post-filterbankAggregate rate transmitted over fiber: 330 Gb/sTransmission distance = 1 to 3 km

    **The partners who have a signed MoU*Where is the MWA and why. Low population density implies low RFI environment*Each tile is a collection of 4x4 dipoles, there are tiles to a node. The entire array has 64 nodes (512 tiles) and the bulk of the collecting area (> 95%) is inside a 1.5 km diameter. There are 16 tiles sprinkled out to a dia of ~3 km (not shown in this figure)*Some views of the production tile, I included it because I had it, there are some nice mechanical engineering features here, but I suspect that you will be too short of time to get into those. If you are interested I can send you a short write up.***A system engineering block diagram, I have highlighted the parts where SHI related work is done. Would you like to walk people through this, you might find the design overview chapter in the Project Book (Knowledge Tree folder Project Office -> Project book) useful http://mwa-lfd.haystack.mit.edu/knowledgetree/view.php?fDocumentId=199This should give people a good idea of the overall structure of the array. It basically builds up the array from the dipoles to the tiles to the nodes and the entire array. Though the array design here does not show it, the array will include 16 tiles outside the 1.5 km dia circle. The primary motivation for these tiles is to increase the resolution of the array to make it more useful for solar imaging. It might be worth mentioning it to this audience. BTW, to give you a feel for the background picture, the breakaway you see is almost aligned NS and is ~260m in length. The MWA site is due East of the breakaway and the region being considered for core is probably a little outside the edge of the image.**A summary of useful design specs, I have marked the ones you might want to highlight**The Aperture plane shows the actual layout of tiles on the site and the uv plane shows the equivalent mirror corresponding to a snap-shot, mono-chromatic observation of the zenith. I have included a similar figure for the data which we have, to allow people to get a feel for the performance of the 32 T system vs the 6 T system for which the data is being presented.

    *****I have included a slide to introduce the EoR science concept. I have a feeling that you will probably be rushed for time. This might be one of the expendable slides.**