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EGRET observations of the BL Lacertae objects 0716+714 and 0521-365During the Compton Observatory's viewing programs Phase 1 (1991 April to 1992 November, also known as the All-Sky Survey) and Phase 2 (1992 November to 1993 September), the BL Lac object 0716+714 was in the field of view of the EGRET telescope a total of six times, three times in Phase 1 and three more times in Phase 2, while the BL Lac object 0521-365 was in the field of view of EGRET only once in Phase 1. The source 0716+714 was detected in high-energy gamma rays by EGRET at a flux level of (2.0 +/- 0.4) x 10(exp -7) photons/sq cm/s for E greater than 100 MeV with a 6 sigma significance when it was first observed by EGRET in 1992 January 10 to 23. The corresponding spectral slope of the photon number distribution is determined to be -2.04 +/- 0.33. The gamma-ray flux of 0716+714 showed considerable time variability in subsequent EGRET observations. But the spectral slope stayed about the same within the statistical uncertainties of the EGRET data. The average spectral slope of the four viewing periods during which the photon flux of 0716+714 stayed above the EGRET detection threshold is found to be -1.85 +/- 0.20 from the combined data. The source 0521+365 was detected by EGRET in 1992 May 14 to June 4 at a flux level of (1.8 +/- 0.5) x 10(exp -7) photons/sq cm/s for E greater than 100 MeV with a 4 sigma significance. The corresponding spectral slope of the photon number distribution is found to be 2.16 +/- 0.36. Details of the observations of these two BL Lac objects with the EGRET telescope are presented.
Document ID
19950054909
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Lin, Y. C.
(Stanford Univ. Stanford, CA, United States)
Bertsch, D. L.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Dingus, B. L.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Esposito, J. A.
(NASA Goddard Space Flight Center 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-Institut fuer Extraterrestrische Physik Garching, Germany)
Kniffen, D. A.
(Hampden-Sydney College, Hampden-Sydney, VA United States)
Mayer-Hasselwander, H. A.
(Max-Planck-Institut fuer Extraterrestrische Physik Garching, Germany)
Date Acquired
August 16, 2013
Publication Date
March 20, 1995
Publication Information
Publication: The Astrophysical Journal, Part 1
Volume: 442
Issue: 1
ISSN: 0004-637X
Subject Category
Astronomy
Accession Number
95A86508
Funding Number(s)
CONTRACT_GRANT: NAG5-31210
CONTRACT_GRANT: NAG5-1605
CONTRACT_GRANT: NAG5-1742
Distribution Limits
Public
Copyright
Other

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