Optical and UV Spectrophotometric Standard Stars
Contact Jack Dembicky for web page errors, corrections, ommisions, and/or additions.
This page last updated: June 9, 2005 - JMD
This page last checked: November 7, 2004 - JMD
HST Spectrophotometric Standards
The HST project has identified six types of calibration targets essential to the good calibration of HST data:
- UV spectrophotometric calibrations stars
- Optical photometric and spectrophotometric calibration stars
- Wavelength calibration targets
- Astrometric calibration fields
- Polarimetric calibration targets
- Spatial flat field targets
Turnshek et al. (AJ, 99, 1243, 1990) list the calibration targets and provide finding charts. Bohlin et al. (ApJS, 73, 413, 1990) discuss the UV calibration of HST standards from IUE data. The basic data for the UV and optical spectrophotometric standards are held in the database CALOBS at STScI. The data are also available through anonymous ftp (ftp://ftp.stsci.edu/cdbs/cdbs2/calobs). Bohlin and Lindler (1992) provide details of the calibration data that are available.
The conversion of the IUE, HST FOS and optical spectra into standard star spectra on the white dwarf primary spectrophotometric scale (Bohlin, Colina & Finlay, AJ, 110, 1316, 1995) is described by Bohlin (Proceedings of STScI HST Calibration Workshop, eds. A. Koratkar & C. Leitherer, p. 49, 1994) and Bohlin (AJ, 111, 1743, 1996). There are spectra available for 23 stars in this white dwarf flux system and the data are held in the CALSPEC data base at STScI.
The data for the 23 stars in the white dwarf spectrophotometric system and a further 7 stars with IUE and model fluxes (indicated by an M in the last column of the table below) have been converted to ABMAG and to flux (ergs/cm/cm/s/A) 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.
Star Name alpha (2000) delta Spec. STMAG Oke (1990) Model opt.
Type (5460A) fluxes spectra
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Zeta Cas (HR153) 00 36 58.30 +53 53 48.9 B2 IV 3.63 M
BPM 16274 00 50 03.18 -52 08 17.4 DA2 14.36 M
GD 50 03 48 50.06 -00 58 30.4 DA2 14.05 *
Hz4 03 55 21.70 +09 47 18.7 DA4 14.45 *
LB227 04 09 28.76 +17 07 54.4 DA4 15.24
Hz2 04 12 43.51 +11 51 50.4 DA3 14.02
Mu Col (HR1996) 05 45 59.92 -32 18 23.4 O9 V 5.15 M
HD 49798 06 48 04.64 -44 18 59.3 O6 8.31 M
HD 60753 07 33 27.26 -50 35 03.7 B3 IV 6.60 M
BD+75d325 08 10 49.31 +74 57 57.5 O5p 9.51 *
AGK+81d266 09 21 19.06 +81 43 28.6 sdO 11.88
GD 108 10 00 47.33 -07 33 31.2 sdB 13.57 *
Feige 34 10 39 36.71 +43 06 10.1 DO 11.12 *
HD 93521 10 48 23.51 +37 34 12.8 O9 Vp 6.95 *
Gamma UMa (HR4554) 11 53 49.83 +53 41 41.1 A0 V 2.59 M
Hz21 12 13 56.42 +32 56 30.8 DO2 14.67 *
Hz44 13 23 35.37 +36 08 00.0 sdO 11.68 *
GRW+70d5824 13 38 51.77 +70 17 08.5 DA3 12.80 *
Eta UMa (HR5191) 13 47 32.44 +49 18 48.0 B3 V 1.83 M
BD+33d2642 15 51 59.86 +32 56 54.8 B2 IV 10.73 *
Alpha Lyr (HR7001) 18 36 56.33 +38 47 01.1 A0 V -0.01
LDS749B 21 32 15.75 +00 15 13.6 DB4 14.71
BD+28d4211 21 51 11.07 +28 51 51.8 Op 10.47 *
G93-48 21 52 25.33 +02 23 24.3 DA3 12.74
NGC 7293 Star 22 29 38.46 -20 50 13.3 Hot 13.48 *
Feige 110 23 19 58.39 -05 09 56.1 DOp 11.80 *
STMAG = -2.5 log10(F(lam)) - 21.10, where F(lam) is in ergs/cm/cm/s/A.
