A survey for transients and variables with the murchison widefield array 32-tile prototype at 154 MHz

M. E. Bell, T. Murphy, D. L. Kaplan, P. Hancock, B. M. Gaensler, J. Banyer, K. Bannister, C. Trott, N. Hurley-Walker, R. B. Wayth, J. P. Macquart, W. Arcus, D. Barnes, G. Bernardi, J. D. Bowman, F. Briggs, J. D. Bunton, R. J. Cappallo, B. E. Corey, A. DeshpandeL. Desouza, D. Emrich, R. Goeke, L. J. Greenhill, B. J. Hazelton, D. Herne, J. N. Hewitt, M. Johnston-Hollitt, J. C. Kasper, B. B. Kincaid, R. Koenig, E. Kratzenberg, C. J. Lonsdale, M. J. Lynch, S. R. Mcwhirter, D. A. Mitchell, M. F. Morales, E. Morgan, D. Oberoi, S. M. Ord, J. Pathikulangara, T. Prabu, R. A. Remillard, A. E.E. Rogers, A. Roshi, J. E. Salah, R. J. Sault, N. Udaya Shankar, K. S. Srivani, J. Stevens, R. Subrahmanyan, S. J. Tingay, M. Waterson, R. L. Webster, A. R. Whitney, A. Williams, C. L. Williams, J. S.B. Wyithe

Research output: Contribution to journalArticle

38 Scopus citations

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.

Original languageEnglish (US)
Article numberstt2200
Pages (from-to)352-367
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Volume438
Issue number1
DOIs
StatePublished - Feb 1 2014
Externally publishedYes

Keywords

  • Catalogues
  • Instrumentation: interferometers
  • Radio continuum: general
  • Techniques: image processing

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Bell, M. E., Murphy, T., Kaplan, D. L., Hancock, P., Gaensler, B. M., Banyer, J., Bannister, K., Trott, C., Hurley-Walker, N., Wayth, R. B., Macquart, J. P., Arcus, W., Barnes, D., Bernardi, G., Bowman, J. D., Briggs, F., Bunton, J. D., Cappallo, R. J., Corey, B. E., ... Wyithe, J. S. B. (2014). 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), 352-367. [stt2200]. https://doi.org/10.1093/mnras/stt2200