CHILES VII: Deep Imaging for the CHILES project, a SKA prototype
  Radio Astronomy is undergoing a renaissance, as the next-generation of
instruments provides a massive leap forward in collecting area and therefore
raw sensitivity. However, to achieve this theoretical level of sensitivity in
the science data products we need to address the much more pernicious
systematic effects, which are the true limitation. These become all the more
significant when we consider that much of the time used by survey instruments,
such as the SKA, will be dedicated to deep surveys.
  CHILES is a deep HI survey of the COSMOS field, with 1,000 hours of VLA time.
We present our approach for creating the image cubes from the first Epoch, with
discussions of the methods and quantification of the data quality from 946 to
1420MHz -- a redshift range of 0.5 to 0. We layout the problems we had to solve
and describe how we tackled them. These are of importance as CHILES is the
first deep wideband multi-epoch HI survey and it has relevance for ongoing and
future surveys.
  We focus on the accumulated systematic errors in the imaging, as the goal is
to deliver a high-fidelity image that is only limited by the random thermal
errors. To understand and correct these systematic effects we ideally manage
them in the domain in which they arise, and that is predominately the
visibility domain. CHILES is a perfect test bed for many of the issues we can
expect for deep imaging with the SKA or ngVLA and we discuss the lessons we
have learned.
