  USNO Bright Star Catalog (UBSC) is a new astrometric catalog of 1423
brightest stars covering the entire sky, which is published online. It is
nearly complete to $V=3$ mag except for three stellar systems. A combined
astrometric solution of the Hipparcos Intermediate Astrometry Data and two
dedicated ground-based campaigns in 2013 -- 2020 is the basis for this catalog.
The astrometric parameters for each star include position coordinates,
parallax, proper motion components, and their covariances on the Hipparcos mean
epoch 1991.25. 64 percent of the catalog are flagged as known or suspected
double or binary stars. UBSC lists 68 stars missing in Gaia EDR3 and another
114 stars without Gaia parallaxes or proper motions. The formal precision
achieved for proper motions is comparable to that of Gaia.
