ASKAP Commissioning Observations of the GAMA 23 Field
  We have observed the G23 field of the Galaxy And Mass Assembly (GAMA) survey
using the Australian Square Kilometre Array Pathfinder (ASKAP) in its
commissioning phase, to validate the performance of the telescope and to
characterize the detected galaxy populations. This observation covers $\sim$48
deg$^2$ with synthesized beam of 32.7$^{\prime\prime}$ by 17.8$^{\prime\prime}$
at 936 MHz, and $\sim$39 deg$^2$ with synthesized beam of 15.8$^{\prime\prime}$
by 12.0$^{\prime\prime}$ at 1320 MHz. At both frequencies, the r.m.s.
(root-mean-square) noise is $\sim$0.1 mJy/beam. We combine these radio
observations with the GAMA galaxy data, which includes spectroscopy of galaxies
that are i-band selected with a magnitude limit of 19.2. Wide-field Infrared
Survey Explorer (WISE) infrared (IR) photometry is used to determine which
galaxies host an active galactic nucleus (AGN). In properties including source
counts, mass distributions, and IR vs. radio luminosity relation, the ASKAP
detected radio sources behave as expected. Radio galaxies have higher stellar
mass and luminosity in IR, optical and UV than other galaxies. We apply optical
and IR AGN diagnostics and find that they disagree for $\sim$30% of the
galaxies in our sample. We suggest possible causes for the disagreement. Some
cases can be explained by optical extinction of the AGN, but for more than half
of the cases we do not find a clear explanation. Radio sources are more likely
($\sim$6%) to have an AGN than radio quiet galaxies ($\sim$1%), but the
majority of AGN are not detected in radio at this sensitivity.
