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X-ray observations of a flare in NGC 4151 from OSO 8The 2-60-keV flux from NGC 4151 has been observed to change by a factor of 2 on a time scale of 1.5 days. No fluctuations in excess of a factor of 3 are detected on time scales less than 4 hours. During a total observation of approximately 11 days there were no statistically significant changes in spectral shape. The spectrum can be fitted by a power law with photon index of about 1.42 + or - 0.06 and a hydrogen column density of approximately 7.5 + or - 0.5 x 10 to the 22nd power atoms/sq cm. A 2-sigma residual to this fit implies fluorescent Fe line emission with an equivalent width of about 240 eV. Both synchrotron self-Compton and thermal Compton models are consistent with the X-ray data.
Document ID
Document Type
Reprint (Version printed in journal)
External Source(s)
Mushotzky, R. F. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Holt, S. S. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Serlemitsos, P. J. (NASA Goddard Space Flight Center Laboratory for High Energy Astrophysics, Greenbelt, Md., United States)
Date Acquired
August 9, 2013
Publication Date
November 1, 1978
Publication Information
Publication: Astrophysical Journal
Subject Category
Distribution Limits