Intermediate-Brightness Equatorial Spectrophotometric Standards

Abstract

We have obtained spectral energy distributions for 41 7m 8m stars near the celestial equator (δ=±3°). The λλ3100 7600 Å spectral range is studied with a spectral resolution of 50 Å. The relative rms error in the visible is 1 2%, increasing to 3 5% towards the edges of the wavelength interval studied. All stars are referenced to a single standard, the circumpolar star HD 221525. The synthetic colors of common stars are compared with those observed in four photometric systems: U BV, W BV R, uvby, and that of the TYCHO catalog. The program stars are recommended as secondary spectrophotometric standards.