The COSMOS2015 Catalog: Exploring the 1<z<6 Universe with half a million
  galaxies
  We present the COSMOS2015 catalog which contains precise photometric
redshifts and stellar masses for more than half a million objects over the
2deg$^{2}$ COSMOS field. Including new $YJHK_{\rm s}$ images from the
UltraVISTA-DR2 survey, $Y$-band from Subaru/Hyper-Suprime-Cam and infrared data
from the Spitzer Large Area Survey with the Hyper-Suprime-Cam Spitzer legacy
program, this near-infrared-selected catalog is highly optimized for the study
of galaxy evolution and environments in the early Universe. To maximise catalog
completeness for bluer objects and at higher redshifts, objects have been
detected on a $\chi^{2}$ sum of the $YJHK_{\rm s}$ and $z^{++}$ images. The
catalog contains $\sim 6\times 10^5$ objects in the 1.5 deg$^{2}$
UltraVISTA-DR2 region, and $\sim 1.5\times 10^5$ objects are detected in the
"ultra-deep stripes" (0.62 deg$^{2}$) at $K_{\rm s}\leq 24.7$ (3$\sigma$, 3",
AB magnitude). Through a comparison with the zCOSMOS-bright spectroscopic
redshifts, we measure a photometric redshift precision of $\sigma_{\Delta
z/(1+z_s)}$ = 0.007 and a catastrophic failure fraction of $\eta=0.5$%. At
$3<z<6$, using the unique database of spectroscopic redshifts in COSMOS, we
find $\sigma_{\Delta z/(1+z_s)}$ = 0.021 and $\eta=13.2\% $. The deepest
regions reach a 90\% completeness limit of 10$^{10}M_\odot$ to $z=4$. Detailed
comparisons of the color distributions, number counts, and clustering show
excellent agreement with the literature in the same mass ranges. COSMOS2015
represents a unique, publicly available, valuable resource with which to
investigate the evolution of galaxies within their environment back to the
earliest stages of the history of the Universe. The COSMOS2015 catalog is
distributed via anonymous ftp
(ftp://ftp.iap.fr/pub/from_users/hjmcc/COSMOS2015/) and through the usual
astronomical archive systems (CDS, ESO Phase 3, IRSA).
