  The mission concept, Cosmic Origins Through UV Surveys (CETUS) is an all-UV
space mission concept that was selected and funded by NASA for study in 2017.
The main capabilities of CETUS that even Hubble doesn't have are: (1)
wide-field (17.4'x17.4') imaging and spectroscopy of astronomical sources with
<0.5'' resolution; (2) spectral sensitivity to UV radiation at wavelengths as
short as 1000 {\AA}; (3) near-UV multi-object slit spectroscopy; and (4)
rapid-response UV spectroscopy and deep imaging of transients like GW 170817;
and (5) 23 times higher sensitivity to extended sources.
  The main purposes of this CETUS Final Report are to describe the CETUS
scientific program and to demonstrate the maturity of its instrumentation,
which forms the basis of its estimated cost. While there are similarities of
this Final Report to that submitted to NASA in March 2019 by the Goddard Space
Flight Center, there are important differences including the following. *
Science. The science case has been refreshed, deepened, and expanded as a
result of ideas and recommendations expressed in the Astro2020 science white
papers. * Instrumentation. Detailed investigations including a high-level error
budget for focus with implications for thermal management, target acquisition
in the MOS micro-shutter array, contamination control have been carried out. *
Mission Design. The spacecraft and mission operations concepts as developed by
NGIS Gilbert (formerly Orbital ATK) rather than the output of Goddard's Mission
Design Lab have been adopted.. * Technology. Technology maturation plans have
been updated.
