HSOY is a catalog of 583'001'653 objects with precise astrometry based on
PPMXL and Gaia DR1. Typical formal errors at mean epoch in proper motion are
below 1 mas/yr for objects brighter than 10 mag, and about 5 mas/yr at the
faint end (about 20 mag). South of -30 degrees, astrometry is significantly
worse. HSOY also contains, where available, USNO-B, Gaia, and 2MASS
photometry. HSOY's positions and proper motions are given for epoch J2000.
The catalog becomes severely incomplete faintwards of 16 mag in the G-band.
The mean epochs are typically very close to Gaia's J2015.
HSOY still contains about 0.7% spurious close
"binaries" (non-matched stars) from the original USNO-B (marked with non-NULL
clone). Also, failed matches within Gaia DR1 contribute another 1.5% spurious
pairs (marked with non-NULL comp). In both cases, astrometry presumably is
sub-standard.
More information is available at http://dc.g-vo.org/hsoy.
To the extent possible under law, the publisher has waived all copyright and related or neighboring rights to HSOY. For details, see the `Creative Commons CC0 1.0 Public Domain dedication <http://creativecommons.org/publicdomain/zero/1.0/>`_. Of course, you should still give proper credit when using this data as required by good scientific practice.
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