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Title: A survey for transients and variables with the Murchison Widefield Array 32-tile prototype at 154 MHz
Authors: Bell, M.E.
Murphy, Tara
Deshpande, A.A.
Prabu, T.
Roshi, Anish D.
Udaya Shankar, N.
Srivani, K.S.
Subrahmanyan, Ravi
+25 Co-authors
Issue Date: Feb-2014
Publisher: Oxford University Press for the Royal Astronomical Society
Citation: Monthly Notices of the Royal Astronomical Society , 2014, Vol. 438, p352-367
Abstract: We present a search for transient and variable radio sources at 154 MHz with the Murchison Widefield Array 32-tile prototype. 51 images were obtained that cover a field of view of 1430 deg2 centred on Hydra A. The observations were obtained over three days in 2010 March and three days in 2011 April and May. The mean cadence of the observations was 26 min and there was additional temporal information on day and year time-scales. We explore the variability of a sample of 105 low-frequency radio sources within the field. Four bright (S > 6 Jy) candidate variable radio sources were identified that displayed low levels of short time-scale variability (26 min). We conclude that this variability is likely caused by simplifications in the calibration strategy or ionospheric effects. On the time-scale of 1 yr we find two sources that show significant variability. We attribute this variability to either refractive scintillation or intrinsic variability. No radio transients were identified and we place an upper limit on the surface density of sources ρ < 7.5 × 10−5 deg−2 with flux densities >5.5 Jy, and characteristic time-scales of both 26 min and 1 yr.
Description: Restricted Access. An open-access version is available at (one of the alternative locations)
ISSN: 0035-8711
1365-2966 - (online)
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Copyright: 2013 The Authors & the Royal Astronomical Society.
Appears in Collections:Research Papers (A&A)

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