The All-Sky Portable (ASP) optical catalog

This "All-Sky Portable" (ASP) catalogue has 1,110,540,822 optical sources, de-duplicated, and stored at 7 bytes per object and so totalling 7.2Gb for the full catalogue, zipped to 5.5Gb and so compact enough to be downloadable over the internet. There are 18 zip files, each of which contains 12 ASP files.

Data is from the APM (http://www.ast.cam.ac.uk/~mike/apmcat), USNO-B & USNO-A (http://www.nofs.navy.mil), and SDSS (http://sdss.org) with astrometry accurate to 1-2 arcsec, and red-blue photometry often recalibrated. This catalogue consists of 216 files, with file data presenting astrometry as offsets from the west-equatorial corner of each file, red and blue optical magnitudes (x10 and rounded), and flags for PSF classes, source survey, variability and nominal proper motion. Simple processing converts this to arcsecond-precision J2000 astrometry and red-blue photometry to a tenth magnitude precision.