Spectrophotometric standards

Abstract

Spectrophotometry for 25 stars intended to be used as standards is presented. These stars were mainly selected for having nearly featureless spectra, making them suitable for use at various resolutions. Sixteen of these have not had previous spectrophotometry published, and eight are fainter than V = 14. Also presented are improved data for nine of the stars observed by Stone (1974, 1977) and Oke (1974). The wavelength coverage is from 3200 to 8100 A, and the magnitudes are on the Hayes-Latham system. On the average, the night-to-night photometric precision of the data is better than 0.01 mag. The external agreement with stars in common with Stone is typically better than 0.03 within 50 A bandpasses. Magnitudes are presented using the same bandpasses employed by Stone, as well as at more frequent wavelengths in order to facilitate the flux calibration of data obtained with high resolution or small detectors (e.g., CCDs). Other bandpasses can be constructed from the data, which are made available via the Astronomical Data Center.