Spectrophotometry of flux calibration stars for Hubble Space Telescope

Fluxes are presented for 103 stars which were observed for Hubble Space Telescope (HST) calibration. Perhaps the most important aspect of this work is confirmation of a revised zero point for optical flux calibration of HST as described by Colina and Bohlin from synthetic photometry. Two cautions are offered for users of the Oke and Gunn spectrophotometric system, and simple corrections are suggested. The present stars are of interest because of their accessibility and their importance in a variety of standard systems. Included are UV and optical spectrophotometric flux standards, UBVRI and IR photometric standards, and many stars from the Equatorial Selected Areas for which UBVRI colors exist as well. It is hoped that the present data will be of use to those relating results between systems. The spectra generally cover the range lambda lambda 4040-8800, with a nominal resolution of about 5.5 Angstrom pixel(-1). The data are referred to the absolute calibration of alpha Lyrae recommended by Megessier. Tabular magnitude values for Hayes and Oke-Gunn wavelengths are presented. The same tables as well as mean magnitudes within 25 Angstrom bins every 25 Angstrom in ASCII and PostScript format, and flux-calibrated spectra, may be obtained from the author.