A group headed by R. Bohlin at STScI have established a set of four white dwarf standards based on comparison of White Dwarf model atmospheres with HST FOS spectra. They are described in Bohlin, Colina & Finlay, AJ, 110, 1316, 1995.The wavelength coverage is 10Å to 3 microns. Extension of the white dwarf primary standards to more stars, giving 27 in total, are described in Bohlin (Proceedings of STScI HST Calibration Workshop, eds. A. Koratkar & C. Leitherer, p. 49, 1994) and in Bohlin (AJ, 111, 1743, 1996).

The hydrogen white dwarfs (see list below) cover a wide range in effective temperature and the FOS spectrophotometry agrees with the model fluxes to within 2% over the whole UV-visible range. In addition, the simulated B and V magnitudes of the data agree to better than 1% with Landolt photometry. Bohlin et al. (1995) recommend these four White Dwarf standards as primary reference standards for all UV and optical calibrations from 1000 to >10000Å.

The data are stored as flux values (ergs/cm/cm/s/A). They have also been converted to ABMAG using the formula
ABMAG = -2.5 alog10(Fnu) - 48.59
(Hamuy et al., PASP, 104, 533, 1992), where Fnu is in ergs/cm/cm/s/Hz.

                     WD Primary Standard Stars

 

   Star       RA (J2000) Dec       B-V     V    Type  Teff  Log g

            d  m  s     d  ' ''                       (K)

-------------------------------------------------------------------

 G191-B2B  05 05 30.6 +52 49 54  -0.326  11.781  DA0  61300  7.50

 GD 71     05 52 27.5 +15 53 17  -0.249  13.032  DA1  32300  7.73

 GD 153    12 57 02.4 +22 01 56  -0.286  13.346  DA1  38500  7.67

 HZ 43     13 16 22.0 +29 05 57  -0.302  12.914  DA1  50000  8.00