The Murchison Widefield Array: From Commissioning to
Observing
The Murchison Widefield Array: From Commissioning to ObservingD.
Oberoi1,2, I. H. Cairns3, L. D. Matthews2 and L. Benkevitch2 on
behalf of the MWA Collaboration
1 National Centre for Radio Astrophysics, TIFR, India2 MIT
Haystack Observatory, USA3 School of Physics, Univ. of Sydney,
Australia OutlineMurchison Widefield Array An introductionCurrent
status and near term plansSome recent results from the MWAThe
Murchison Widefield ArrayLow radio frequency interferometer (80-300
MHz)Key Design ConsiderationsExploit the advances in Digital Signal
Processing and affordability of computing.Emphasis on quality
calibrationOptimize the design for carefully chosen science
targetsSimplify the problem to the extent possibleKey Design
FeaturesLarge N (no. of interferometer elements)Compact footprint
(max baseline ~3 km)Operation at higher end of the low radio
frequency rangeRadio quiet location - Western Australian
OutbackHumans ~ 4x10-3 humans km-2
3MWA: Key Science ProjectsEpoch of Reionization21cm hyperfine
transition line of neutral hydrogen, red-shifted to frequencies
below 200 MHzFlagship science application, but very
challengingGalactic and Extra-galactic ScienceConfusion limited
all-sky survey with full polarimetry and good spectral
resolutionTime domain astrophysicsKnown and not yet known
transientsSolar, Heliospheric and Ionospheric ScienceSpectroscopic
solar imagingIPS and Faraday rotation studies of the
HeliosphereIonospheric propagation effects
AOGS, Brisbane, June 2013
This 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.5
X Axis spans 30.72 MHz (~140-170 MHz); Y Axis spans ~10 minMWA:
uv coverage
Very Large ArrayNM, USA
351 baselines27 elements
8128 baselines128 elementsMWA: Current StatusInstrument
re-scoped to 128 tiles (~early 2011)
Status as of June 2012Site infrastructure Site survey for
marking tile locations and trench paths Trenching Laying power and
optical fiber cables Building receiver pads Hardware installation
Tiles - all 128 Beamformers all 128AOGS-AGU Joint Assembly,
Singapore August 2012Aug. 2012, AOGSMWA: Current
StatusCommissioning Period (June 2012 June 2013) Test and
commission the array in 5 groups of 32 tiles each (June 12 Dec 12)
Install the 128T correlator to run the entire array as a single
instrument Commission the 128T as a single instrument Commissioning
report accepted on June 20, 2013 at MWA Project meeting in Seattle,
WA.Formal end of the commissioning periodOne year period of shared
risk observing starts Jul 2013Jul-Dec 2013 Open only to MWA Project
membersJan-Jun 2014 Significant amount of Open Skies observing
time
AOGS, Brisbane, June 2012MWA: Solar Observations ProposalLead by
Cairns and Oberoi Unbiased solar observingIn-depth investigations
concentrate disproportionately on what is deemed to be
interesting.Exploring new phase space discovery potential avoid
application of any a-priori bias 30 hours (19 TB)1 hr/day for a
month, at the same UT slotSame observing mode (12 chunks of 2.56
MHz distributed from 80 to 300 MHz); 1s, 40 kHz
resolutionObservations for Interplanetary Scintillation (IPS),
Ionospheric Scintillation, satellite radio beacons all require high
time resolution data (~20ms) voltage beamformer to provide this is
currently under development expect to conduct proof-of-principle
observations using Directors Discretionary Time
GRANTEDCommissioning Highlights
Andrea Offringa (ANU) and the MWA Commissioning Team
Commissioning HighlightsSouthern Galactic Plane Mosaic Ben McKinley
(ANU), Natasha Hurley-Walker (Curtin), Randall Wayth (Curtin) and
the MWA Science Commissioning Team
Commissioning Highlights: Solar Imaging
16 May, 201304:15:02 UT
0=153.905 MHz=640 kHz
t=1 second
Imaging Dynamic Range ~1500
Radio Movie
16 May, 201304:11:04 04:16:00 UT
0=153.905 MHz=640 kHz
t=1 second
Imaging Dynamic Range ~1500
Spatial Variability of Radio Emission
20%70%250%600%15ConclusionsCommissioning successfully completed
on schedule.Shared risk observing commences next month.MWA is
exceptionally well suited for solar imaging - represents the
state-of-the-art for the high dynamic range, high fidelity imaging
at low radio frequencies.
Open Skies policy - observing proposals from the community are
invited for period starting Jan 2014.Visit
http://www.mwatelescope.org for more information
If you would like to get involved [email protected] (Divya
Oberoi)Baselines and u-v plane
The u-v plane, except that units on the axes should have been ,
not lengthNBaselines = N(N-1)/2(uij, vij)(-uij,-vij)u () v ()17
25 Sep, 201104:08:50 04:18:47 UT
0=152.3 MHz=80 kHz
t=1 second
Imaging Dynamic Range ~5500