This schema contains data re-published from the official
Gaia mirrors (such as ivo://uni-heidelberg.de/gaia/tap) either to
support combining its data with local tables (the various Xlite tables)
or to make the data more accessible to VO clients (e.g., epoch fluxes).
PPMXL is a catalog of positions, proper motions, 2MASS- and optical
photometry of 900 million stars and galaxies, aiming to be complete
down to about V=20 full-sky. It is the result of a re-reduction of
USNO-B1 together with 2MASS to the ICRS as represented by PPMX.
