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Detection of gamma-ray emission from the quasar PKS 0208-512High-energy gamma-ray emission has been detected from the quasar PKS 0208-512 in the energy range above 30 MeV by the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory. This region of sky was observed in five different viewing periods, and evidence of time variability in the gamma-ray emission by more than a factor of 3 was found. At the maximum intensity between 1991 September 19 and October 3, the flux density above 100 MeV was (9.1 +/- 0.4) x 10 exp -7 gamma/sq cm per sec. The photon spectrum during this period may be expressed as a power law with an exponent of - 1.69 +/- 0.05 between 30 MeV and 4 GeV. This is the hardest quasar spectrum observed by EGRET up to the present time.
Document ID
19930044668
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
doi:10.1086/186756
Authors
Bertsch, D. L. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Dingus, B. L. (NASA Goddard Space Flight Center; Universities Space Research Association, Greenbelt, MD, United States)
Fichtel, C. E. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hartman, R. C. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hunter, S. D. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Kanbach, G. (Max-Planck-Inst. fuer Extraterrestrische Physik Garching, Germany)
Kniffen, D. A. (Hampden-Sydney College VA, United States)
Lin, Y. C. (Stanford Univ. CA, United States)
Mattox, J. R. (NASA Goddard Space Flight Center; Compton Observatory Greenbelt, MD, United States)
Mayer-Hasselwander, H. A. (Max-Planck-Inst. fuer Extraterrestrische Physik Garching, Germany)
Date Acquired
August 16, 2013
Publication Date
March 1, 1993
Publication Information
Publication: Astrophysical Journal, Part 2 - Letters
Volume: 405
Issue: 1
ISSN: 0004-637X
Subject Category
Astrophysics
Report/Patent Number
ISSN: 0004-637X
Accession Number
93A28665
Funding Number(s)
CONTRACT_GRANT: NAS5-31210
CONTRACT_GRANT: NAG5-1605
CONTRACT_GRANT: BMFT-50-QV-9095
CONTRACT_GRANT: NAG5-1742
Distribution Limits
Public
Copyright
Other

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