A survey for transients and variables with the Murchison Widefield Array
  32-tile prototype at 154 MHz
  We present a search for transient and variable radio sources at 154 MHz with
the Murchison Widefield Array 32-tile prototype. Fifty-one images were obtained
that cover a field of view of 1430 deg^2 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 minutes and there was
additional temporal information on day and year timescales. 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 timescale variability (26 minutes). We conclude
that this variability is likely caused by simplifications in the calibration
strategy or ionospheric effects. On the timescale of one year 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
rho < 7.5 x 10^-5 deg^-2 with flux densities > 5.5 Jy, and characteristic
timescales of both 26 minutes and one year.
