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

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

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

Citation

Bell, ME and Murphy, T and Kaplan, DL and Hancock, P and Gaensler, BM and Banyer, J and Bannister, K and Trott, C and Hurley-Walker, N and Wayth, RB and Macquart, J-P and Arcus, W and Barnes, D and Bernardi, G and Bowman, JD and Briggs, F and Bunton, JD and Cappallo, RJ and Corey, BE and Deshpande, A and deSouza, L and Emrich, D and Goeke, R and Greenhill, LJ and Hazelton, BJ and Herne, D and Hewitt, JN and Johnston-Hollitt, M and Kasper, JC and Kincaid, BB and Koenig, R and Kratzenberg, E and Lonsdale, CJ and Lynch, MJ and McWhirter, SR and Mitchell, DA and Morales, MF and Morgan, E and Oberoi, D and Ord, SM and Pathikulangara, J and Prabu, T and Remillard, RA and Rogers, AEE and Roshi, A and Salah, JE and Sault, RJ and Udaya Shankar, N and Srivani, KS and Stevens, J and Subrahmanyan, R and Tingay, SJ and Waterson, M and Webster, RL and Whitney, AR and Williams, A and Williams, CL and Wyithe, JSB, A survey for transients and variables with the Murchison Widefield Array 32-tile prototype at 154 MHz, Monthly Notices of the Royal Astronomical Society, 438, (1) pp. 352-367. ISSN 0035-8711 (2014) [Refereed Article]

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DOI: doi:10.1093/mnras/stt2200

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.

Item Details

Item Type:	Refereed Article
Keywords:	instrumentation: interferometers, techniques: image processing, catalogues, radio continuum: general
Research Division:	Physical Sciences
Research Group:	Astronomical and Space Sciences
Research Field:	Galactic Astronomy
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Physical Sciences
UTAS Author:	Stevens, J (Dr Jamie Stevens)
ID Code:	98588
Year Published:	2014
Web of Science^® Times Cited:	36
Deposited By:	Mathematics and Physics
Deposited On:	2015-02-19
Last Modified:	2015-04-27
Downloads:	278 View Download Statistics

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