C2A is able to access the USNO-B1.0 catalogue directly via the CDS Internet site VizieR. The catalogue contains 1,045,913,669 objects and occupies more than 80 GigaBytes of disc space. This catalogue can be selected in the Options dialogue box (Stars tab), then the stars in the catalogue are loaded then displayed by using the USNO-B1.0 Catalogue... command in the File menu (or else by using the Load USNO-B1.0 command in the contextual command you get by right-clicking on the map).
You select the USNO-B1.0 catalogue as the current catalogue through the Stars tab of the Options dialogue box, or by SHIFT-right-clicking on the map. You can choose whether to display the blue magnitude or the red magnitude by clicking the Advanced options... button on the Stars tab of the Options dialogue box.
The information associated with each star in the catalogue is as follows:
- the red magnitude
- the blue magnitude
- the right ascension
and declination for the epoch 2000
- proper motions in
right ascension and declination
- position errors
- proper motion errors