White Dwarf Standard Stars: G191-B2B, GD 71, GD 153, HZ 43

Three additional white dwarfs, GD 71, GD 153, and HZ 43, covering a wide range in effective temperature, have been observed with HST faint object spectrograph (FOS) to check the G191 -B2B white dwarf based absolute calibration of HST instruments. The FOS spectrophotometry of the three additional white dwarfs agree with model spectra to ∼2%. The FOS absolute flux of G19l -B2B, GD 71, and GD 153 agree with Landolt photometry to better than 1% on average, in B and V. Consequently, the white dwarfs G191 -B2B, GD 71, GD 153, and HZ 43 are the primary reference standards that are recommended for all ultraviolet and optical absolute calibrations from 1000 to 10 000 Å.