GPS1 is a catalog using Gaia, PS1, SDSS and 2MASS to compute proper motions.

We got the catalog from Bertrand Goldman via ftp in April 2017; it has a
complex provenance, where the astrometric work was done by Haijun Tian,
then at MPIA, with additional contributions by Branimir Sesar and
probably more.  Bertrand in particular did crossmatches to the source
catalogs to retrieve photometry (yes, that's a bit odd).

There's a website on this at http://www.mpia.de/~tian/GPS1/ (that has
different files from those we got), a draft paper at
https://arxiv.org/abs/1703.06278.

A query interface for Pan-STARRS (for comparison) is at
http://archive.stsci.edu/panstarrs/search.php