These data are a selection of stars supplied by Arlo Landolt to serve as
bright standards of the UBVRI photometric system. They provide internally
consistent homogeneous broadband standards for the Johnson-Kron-Cousins
photometric system for telescopes of intermediate and large size in both
hemispheres. The filter bands have the following effective wavelengths:
U, 3600Å; B, 4400Å; V, 5500Å; R, 6400Å; I, 7900Å.
The positions are taken from the
Naval Observatory Merged Astronomical Database (NOMAD). Positions are
converted to the epoch, equator, and equinox of the middle of the current
year; radial velocities are included in the calculation where available.