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A survey for transients and variables with the Murchison Widefield Array 32-tile prototype at 154 MHz

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posted on 2023-05-18, 07:42 authored by Bell, ME, Murphy, T, Kaplan, DL, Hancock, P, Gaensler, BM, Banyer, J, Bannister, K, Trott, C, Hurley-Walker, N, Wayth, RB, Macquart, J-P, Arcus, W, Barnes, D, Bernardi, G, Bowman, JD, Briggs, F, Bunton, JD, Cappallo, RJ, Corey, BE, Deshpande, A, deSouza, L, Emrich, D, Goeke, R, Greenhill, LJ, Hazelton, BJ, Herne, D, Hewitt, JN, Johnston-Hollitt, M, Kasper, JC, Kincaid, BB, Koenig, R, Kratzenberg, E, Lonsdale, CJ, Lynch, MJ, McWhirter, SR, Mitchell, DA, Morales, MF, Morgan, E, Oberoi, D, Ord, SM, Pathikulangara, J, Prabu, T, Remillard, RA, Rogers, AEE, Roshi, A, Salah, JE, Sault, RJ, Udaya Shankar, N, Srivani, KS, Stevens, J, Subrahmanyan, R, Tingay, SJ, Waterson, M, Webster, RL, Whitney, AR, Williams, A, Williams, CL, Wyithe, JSB
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.

History

Publication title

Monthly Notices of the Royal Astronomical Society

Volume

438

Pagination

352-367

ISSN

0035-8711

Department/School

School of Natural Sciences

Publisher

Blackwell Publishing Ltd

Place of publication

9600 Garsington Rd, Oxford, England, Oxon, Ox4 2Dg

Rights statement

Copyright 2014 the authors

Repository Status

  • Open

Socio-economic Objectives

Expanding knowledge in the physical sciences

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