Cartes du Ciel is free software released under the terms of the
GNU General Public License
USNO-B is an all-sky catalog that presents positions, proper motions, magnitudes in various optical passbands, and star/galaxy estimators for 1,042,618,261 objects derived from 3,643,201,733 separate observations.
The data were obtained from scans of 7,435 Schmidt plates taken for the various sky surveys during the last 50 years.
USNO-B1.0 is believed to provide all-sky coverage, completeness down to V = 21, 0.2 arcsecond astrometric accuracy at J2000, 0.3 magnitude photometric accuracy in up to five colors, and 85% accuracy for distinguishing stars from non-stellar objects.
For more information see: http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/usno-b1.0
You can download this catalog using Bittorent, download size is 46 GB:
Each zip file contain the catalog data for a one degree declination zone.
Unzip each file in the same directory to reproduce the original catalog data. The total size after decompression is 78GB.
The name of each file is the South Polar Distance (DEC+90) of the zone.
You can use any software supporting the USNO-B1.0 Catalog in it's original form.
For use in Skychart see the corresponding documentation page
Please acknowledge the source of the data in your publication, as described in the Copyright file.