The Data Lab hosts both USNO A2 and B1 as astrometric reference datasets. For description of these catalogs, see:
- USNO A2: Naval Oceanography Portal (http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/icas/icas-usno-a2-format)
- Monet et al. 2003, AJ, 125, 984 (http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/icas/2003.AJ.125.984M.pdf)
The usno.a2 table and usno.b1 table have been crossmatched against our default reference datasets within a 1.5 arcsec radius, nearest neighbor only. These tables will appear with x1p5 in their name in our table browser. Example: usno.x1p5__a2__gaia_dr3__gaia_source.