Evolutionary Map of the Universe (EMU):Compact radio sources in the
  SCORPIO field towards the Galactic plane
  We present observations of a region of the Galactic plane taken during the
Early Science Program of the Australian Square Kilometre Array Pathfinder
(ASKAP). In this context, we observed the SCORPIO field at 912 MHz with an
uncompleted array consisting of 15 commissioned antennas. The resulting map
covers a square region of ~40 deg^2, centred on (l, b)=(343.5{\deg},
0.75{\deg}), with a synthesized beam of 24"x21" and a background rms noise of
150-200 {\mu}Jy/beam, increasing to 500-600 {\mu}Jy/beam close to the Galactic
plane. A total of 3963 radio sources were detected and characterized in the
field using the CAESAR source finder. We obtained differential source counts in
agreement with previously published data after correction for source extraction
and characterization uncertainties, estimated from simulated data. The ASKAP
positional and flux density scale accuracy were also investigated through
comparison with previous surveys (MGPS, NVSS) and additional observations of
the SCORPIO field, carried out with ATCA at 2.1 GHz and 10" spatial resolution.
These allowed us to obtain a measurement of the spectral index for a subset of
the catalogued sources and an estimated fraction of (at least) 8% of resolved
sources in the reported catalogue. We cross-matched our catalogued sources with
different astronomical databases to search for possible counterparts, finding
~150 associations to known Galactic objects. Finally, we explored a
multiparametric approach for classifying previously unreported Galactic sources
based on their radio-infrared colors.
