OSSE spectral observations of GX 339-4 and Cyg X-1

D. A. Grabelsky, S. M. Matz, W. R. Purcell, Melville P Ulmer, W. N. Johnson, R. L. Kinzer, R. A. Kroeger, J. D. Kurfess, M. S. Strickman, J. E. Grove, R. A. Cameron, G. V. Jung, M. D. Leising

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations


The Oriented Scintillation Spectrometer Experiment on the Compton Gamma Ray Observatory has carried out spectral and timing observations of Galactic black hole candidates GX 339-4 and Cyg X-1. GX 339-4 was observed as a target of opportunity in 1991 September, in response to the outburst reported by BATSE and SIGMA. The source was detected from 50 to 400 keV, at a level relative to the Crab of ∼30%. During a followup observatio. n made in 1991 November, the intensity of the source below 100 keV had dropped by nearly two orders of magnitude, and it was no longer detected above 100 keV. The observations of Cyg X-1 were made during three different observing periods between 1991 June and November. The OSSE time-averaged spectrum of Cyg X-1 is about 10 times brighter than that of GX 339-4, but remarkably similar in shape over the energy range in which both are detected. No significant emission is seen above about 1 MeV, and there is no evidence for any bumps or narrow lines near 0.511 MeV. The spectra of both sources are decribed reasonably well by a Comptonization model.

Original languageEnglish (US)
Title of host publicationCompton Gamma-Ray Observatory
EditorsNeil Gehrels, Michael W. Friedlander, Daryl J. Macomb
PublisherAmerican Institute of Physics Inc.
Number of pages5
ISBN (Electronic)1563961040
StatePublished - Jan 1 1993
EventCompton Symposium - St. Louis, United States
Duration: Oct 15 1992Oct 17 1992

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


ConferenceCompton Symposium
Country/TerritoryUnited States
CitySt. Louis

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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