Note: see the UCAC4 document, and the the fix for high proper motion stars. The UCAC home page is available at http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/ucac. Please acknowledge the usage of the UCAC4
Note:
Note: SDSS is also available from http://www.sdss3.org/dr9/
Note: The column expnum provides an access to details on the exposures, and a link to the Preview and Retrieval System via the CADC