Deep PSF photometric catalog of the VVV survey data
  The Vista Variables in the Via Lactea (VVV) survey has performed a
multi-epoch near-infrared imaging of the inner Galactic plane. High-fidelity
photometric catalogs are needed to utilize the data. We aim at producing a
deep, point-spread-function (PSF) photometric catalog for the VVV survey J, H,
and Ks band data. Specifically, we aim at taking advantage of all the epochs of
the survey to reach high limiting magnitudes. We develop an automatic
PSF-fitting pipeline based on the DaoPHOT algorithm and perform photometry on
the stacked VVV images in J, H, and Ks bands. We present a PSF photometric
catalog in the Vega system that contains about 926 million sources in the J, H,
and Ks filters. About 10% of the sources are flagged as possible spurious
detections. The 5 sigma limiting magnitudes of the sources with high
reliability are about 20.8, 19.5, and 18.7 mag in the J, H, and Ks band,
respectively, depending on the local crowding condition. Our photometric
catalog reaches on average about one magnitude deeper than the previously
released PSF DoPHOT photometric catalog. It also includes less spurious
detections. There are significant differences in the brightnesses of faint
sources between our catalog and the previously released one. The likely origin
of these differences is in the different photometric algorithms that are
utilized; it is not straightforward to assess which catalog is more accurate in
which situations. Our new catalog is beneficial especially for science goals
that require high limiting magnitudes; our catalog reaches such in fields that
have a relatively uniform source number density. Overall, the limiting
magnitudes and completeness are different in the fields with different crowding
conditions.
