Source counts and confusion at 72-231 MHz in the MWA GLEAM survey
  The GaLactic and Extragalactic All-sky MWA survey (GLEAM) is a radio
continuum survey at 72-231 MHz of the whole sky south of declination +30 deg,
carried out with the Murchison Widefield Array (MWA). In this paper, we derive
source counts from the GLEAM data at 200, 154, 118 and 88 MHz, to a flux
density limit of 50, 80, 120 and 290 mJy respectively, correcting for
ionospheric smearing, incompleteness and source blending. These counts are more
accurate than other counts in the literature at similar frequencies as a result
of the large area of sky covered and this survey's sensitivity to extended
emission missed by other surveys. At S_154MHz > 0.5 Jy, there is no evidence of
flattening in the average spectral index (alpha approx. -0.8 where S
proportional to nu^alpha) towards the lower frequencies. We demonstrate that
the SKA Design Study (SKADS) model by Wilman et al. (2008) significantly
underpredicts the observed 154 MHz GLEAM counts, particularly at the bright
end. Using deeper LOFAR counts and the SKADS model, we find that sidelobe
confusion dominates the thermal noise and classical confusion at nu >~ 100 MHz
due to both the limited CLEANing depth and undeconvolved sources outside the
field-of-view. We show that we can approach the theoretical noise limit using a
more efficient and automated CLEAN algorithm.
