1203.5790 (Christopher L. Williams et al.)

Low Frequency Imaging of Fields at High Galactic Latitude with the Murchison Widefield Array 32-Element Prototype    [PDF]

Christopher L. Williams, Jacqueline N. Hewitt, Alan M. Levine, Angelica de Oliveira-Costa, Judd D. Bowman, Frank H. Briggs, B. M. Gaensler, Lars L. Hernquist, Daniel A. Mitchell, Miguel F. Morales, Shiv K. Sethi, Ravi Subrahmanyan, Elaine M. Sadler, Wayne Arcus, David G. Barnes, Gianni Bernardi, John D. Bunton, Roger C. Cappallo, Brian W. Crosse, Brian E. Corey, Avinash Deshpande, Ludi deSouza, David Emrich, Robert F. Goeke, Lincoln J. Greenhill, Bryna J. Hazelton, David Herne, David L. Kaplan, Justin C. Kasper, Barton B. Kincaid, Ronald Koenig, Eric Kratzenberg, Colin J. Lonsdale, Mervyn J. Lynch, S. Russell McWhirter, %Daniel A. Mitchell, %Miguel F. Morales, Edward H. Morgan, Divya Oberoi, Stephen M. Ord, Joseph Pathikulangara, Thiagaraj Prabu, Ronald A. Remillard, Alan E. E. Rogers, Anish A. Roshi, Joseph E. Salah, Robert J. Sault, N. Udaya Shankar, K. S. Srivani, Jamie B. Stevens, Steven J. Tingay, Randall B. Wayth, Mark Waterson, Rachel L. Webster, Alan R. Whitney, Andrew J. Williams, J. Stuart B. Wyithe

The Murchison Widefield Array (MWA) is a new low-frequency, wide field-of-view radio interferometer under development at the Murchison Radio-astronomy Observatory (MRO) in Western Australia. We have used a 32-element MWA prototype interferometer (MWA-32T) to observe two 50-degree diameter fields in the southern sky in the 110 MHz to 200 MHz band 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. 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 MHz to 200 MHz band.

View original: http://arxiv.org/abs/1203.5790