X-Ray and Optical Observations of Quasars

  • Harvey Tananbaum
  • Herman L. Marshall
Part of the International Astronomical Union / Union Astronomique Internationale book series (IAUS, volume 97)


The first Einstein observations established that quasars, as a class, are luminous X-ray emitters (Tananbaum et al. 1979). Since then, one of our major programs has been to carry out further X-ray and optical observations to improve our estimate of the contribution of quasars to the 2 keV extragalactic isotropic X-ray background and also to reconcile number counts of discrete X-ray sources with reported optical number counts of quasars (cf. Zamorani et al. 1981 and references therein). This paper is a preliminary report on our observations of the 1.7 square degree field studied originally by Braccesi and his colleagues (Formiggini et al. 1980 and Braccesi et al. 1980). A more detailed presentation of our results is in preparation (Marshall et al., 1981).


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Copyright information

© IAU 1982

Authors and Affiliations

  • Harvey Tananbaum
    • 1
  • Herman L. Marshall
    • 1
  1. 1.Harvard-Smithsonian Center for AstrophysicsUSA

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