LOW-FREQUENCY IMAGING OF FIELDS AT HIGH GALACTIC LATITUDE WITH THE MURCHISON WIDEFIELD ARRAY 32 ELEMENT PROTOTYPE

The Murchison Widefield Array (MWA) is a new low-frequency, wide-field-of-view radio interferometer under development at the Murchison Radio-astronomy Observatory in Western Australia. We have used a 32 element MWA prototype interferometer (MWA-32T) to observe two 50[degrees] diameter fields in the...

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Bibliographic Details
Published in:The Astrophysical journal 2012-08, Vol.755 (1), p.1-19
Main Authors: Williams, Christopher L, Hewitt, Jacqueline N, Levine, Alan M, DE OLIVEIRA-COSTA, ANGELICA, Bowman, Judd D, Briggs, Frank H, Gaensler, B M, Hernquist, Lars L, Mitchell, Daniel A, Morales, Miguel F
Format: Article
Language:English
Subjects:
ALGORITHMS
Arrays
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CALIBRATION
COMPARATIVE EVALUATIONS
DATA ANALYSIS
Imaging
INTERFEROMETERS
MHZ RANGE
NORTHERN HEMISPHERE
POINT SOURCES
Pollution sources
Prototypes
RADIOASTRONOMY
RESOLUTION
SKY
STARS
Surveys
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Summary:The Murchison Widefield Array (MWA) is a new low-frequency, wide-field-of-view radio interferometer under development at the Murchison Radio-astronomy Observatory in Western Australia. We have used a 32 element MWA prototype interferometer (MWA-32T) to observe two 50[degrees] diameter fields in the southern sky, covering a total of ~2700 deg super(2), in order to evaluate the performance of the MWA-32T, to develop techniques for epoch of reionization experiments, and to make measurements of astronomical foregrounds. We developed a calibration and imaging pipeline for the MWA-32T, and used it to produce ~15' angular resolution maps of the two fields in the 110-200 MHz band. We perform a blind source extraction using these confusion-limited images, and detect 655 sources at high significance with an additional 871 lower significance source candidates. We compare these sources with existing low-frequency radio surveys in order to assess the MWA-32T system performance, wide-field analysis algorithms, and catalog quality. Our source catalog is found to agree well with existing low-frequency surveys in these regions of the sky and with statistical distributions of point sources derived from Northern Hemisphere surveys; it represents one of the deepest surveys to date of this sky field in the 110-200 MHz band.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/755/1/47