Deep observations of the Super-CLASS super-cluster at 325 MHz with the
  GMRT: the low-frequency source catalogue
  We present the results of 325 MHz GMRT observations of a super-cluster field,
known to contain five Abell clusters at redshift $z \sim 0.2$. We achieve a
nominal sensitivity of $34\,\mu$Jy beam$^{-1}$ toward the phase centre. We
compile a catalogue of 3257 sources with flux densities in the range
$183\,\mu\rm{Jy}\,-\,1.5\,\rm{Jy}$ within the entire $\sim 6.5$ square degree
field of view. Subsequently, we use available survey data at other frequencies
to derive the spectral index distribution for a sub-sample of these sources,
recovering two distinct populations -- a dominant population which exhibit
spectral index trends typical of steep-spectrum synchrotron emission, and a
smaller population of sources with typically flat or rising spectra. We
identify a number of sources with ultra-steep spectra or rising spectra for
further analysis, finding two candidate high-redshift radio galaxies and three
gigahertz-peaked-spectrum radio sources. Finally, we derive the
Euclidean-normalised differential source counts using the catalogue compiled in
this work, for sources with flux densities in excess of $223 \, \mu$Jy. Our
differential source counts are consistent with both previous observations at
this frequency and models of the low-frequency source population. These
represent the deepest source counts yet derived at 325 MHz. Our source counts
exhibit the well-known flattening at mJy flux densities, consistent with an
emerging population of star-forming galaxies; we also find marginal evidence of
a downturn at flux densities below $308 \, \mu$Jy, a feature so far only seen
at 1.4 GHz.
