Abstract
The Cosmic Evolution Survey (COSMOS) has become a cornerstone of
extragalactic astronomy. Since the last public catalog in 2015, a wealth of new
imaging and spectroscopic data has been collected in the COSMOS field. This
paper describes the collection, processing, and analysis of this new imaging
data to produce a new reference photometric redshift catalog. Source detection
and multi-wavelength photometry is performed for 1.7 million sources across the
$2\,deg^2$ of the COSMOS field, $\sim$966,000 of which are measured
with all available broad-band data using both traditional aperture photometric
methods and a new profile-fitting photometric extraction tool, The Farmer,
which we have developed. A detailed comparison of the two resulting photometric
catalogs is presented. Photometric redshifts are computed for all sources in
each catalog utilizing two independent photometric redshift codes. Finally, a
comparison is made between the performance of the photometric methodologies and
of the redshift codes to demonstrate an exceptional degree of self-consistency
in the resulting photometric redshifts. The $i<21$ sources have sub-percent
photometric redshift accuracy and even the faintest sources at $25<i<27$ reach
a precision of $5\,\%$. Finally, these results are discussed in the context of
previous, current, and future surveys in the COSMOS field. Compared to
COSMOS2015, reaches the same photometric redshift precision at almost one
magnitude deeper. Both photometric catalogs and their photometric redshift
solutions and physical parameters will be made available through the usual
astronomical archive systems (ESO Phase 3, IPAC IRSA, and CDS).
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