The

ABSTRACT. Hipparcos and Tycho magnitudes have been extracted for many of the E-region standard stars. Dierences between B, V, and the Hipparcos and Tycho magnitudes have been derived and regressed against color. Fiducial lines and polynomial Ðts have been derived and compared with values in the Hipparcos and Tycho Catalogues. Synthetic photometry has been made using the Vilnius spectra and compared with the observations. As a result, it has been necessary to modify some of the published bandpasses. 1