# USNO-B1.0 Catalog

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

### DOWNLOAD:

You can download this catalog using Bittorent, download size is 46 GB:

- Get the torrent file
- Open the torrent file in your bittorrent client software. You can eventually select only the zone directory you want. Each zip file contain the catalog data for a one degree declination zone, the name of the file is the South Polar Distance (DEC+90) of the zone.
- Please keep seeding to help other to get the data!

### INSTALL:

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.

### USE:

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.