The 31 Deg$^2$ Release of the Stripe 82 X-ray Survey: The Point Source
  Catalog
  We release the next installment of the Stripe 82 X-ray survey point-source
catalog, which currently covers 31.3 deg$^2$ of the Sloan Digital Sky Survey
(SDSS) Stripe 82 Legacy field. In total, 6181 unique X-ray sources are
significantly detected with {\it XMM-Newton} ($>5\sigma$) and {\it Chandra}
($>4.5\sigma$). This catalog release includes data from {\it XMM-Newton} cycle
AO 13, which approximately doubled the Stripe 82X survey area. The flux limits
of the Stripe 82X survey are $8.7\times10^{-16}$ erg s$^{-1}$ cm$^{-2}$,
$4.7\times10^{-15}$ erg s$^{-1}$ cm$^{-2}$, and $2.1\times10^{-15}$ erg
s$^{-1}$ cm$^{-2}$ in the soft (0.5-2 keV), hard (2-10 keV), and full bands
(0.5-10 keV), respectively, with approximate half-area survey flux limits of
$5.4\times10^{-15}$ erg s$^{-1}$ cm$^{-2}$, $2.9\times10^{-14}$ erg s$^{-1}$
cm$^{-2}$, and $1.7\times10^{-14}$ erg s$^{-1}$ cm$^{-2}$. We matched the X-ray
source lists to available multi-wavelength catalogs, including updated matches
to the previous release of the Stripe 82X survey; 88\% of the sample is matched
to a multi-wavelength counterpart. Due to the wide area of Stripe 82X and rich
ancillary multi-wavelength data, including coadded SDSS photometry,
mid-infrared {\it WISE} coverage, near-infrared coverage from UKIDSS and VHS,
ultraviolet coverage from {\it GALEX}, radio coverage from FIRST, and
far-infrared coverage from {\it Herschel}, as well as existing $\sim$30\%
optical spectroscopic completeness, we are beginning to uncover rare objects,
such as obscured high-luminosity AGN at high-redshift. The Stripe 82X point
source catalog is a valuable dataset for constraining how this population grows
and evolves, as well as for studying how they interact with the galaxies in
which they live.
