Milky Way demographics with the VVV survey. IV. PSF photometry from
  almost one billion stars in the Galactic bulge and adjacent southern disk
  The inner regions of the Galaxy are severely affected by extinction, which
limits our capability to study the stellar populations present there. The Vista
Variables in the Via Lactea (VVV) ESO Public Survey has observed this zone at
near-infrared wavelengths where reddening is highly diminished. By exploiting
the high resolution and wide field-of-view of the VVV images we aim to produce
a deep, homogeneous, and highly complete database of sources that cover the
innermost regions of our Galaxy. To better deal with the high crowding in the
surveyed areas, we have used point spread function (PSF)-fitting techniques to
obtain a new photometry of the VVV images, in the ZYJHKs near-infrared filters
available. Our final catalogs contain close to one billion sources, with
precise photometry in up to five near-infrared filters, and they are already
being used to provide an unprecedented view of the inner Galactic stellar
populations. We make these catalogs publicly available to the community. Our
catalogs allow us to build the VVV giga-CMD, a series of color-magnitude
diagrams of the inner regions of the Milky Way presented as supplementary
videos. We provide a qualitative analysis of some representative CMDs of the
inner regions of the Galaxy, and briefly mention some of the studies we have
developed with this new dataset so far.
