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The high-energy pulsed X-ray spectrum of Hercules X-1 as observed with OSO 8Hercules X-1 was observed from August 30 to September 10, 1977, by using the high-energy X-ray scintillation spectrometer on board the OSO 8 satellite. The observation, during which the source was monitored continually for nearly an entire ON-state, covered the energy range from 16 to 280 keV. Pulsed-flux measurements as a function of binary orbit and binary phase are presented for energies between 16 and 98 keV. The pulsed flux between 16 and 33 keV exhibited a sharp decrease following the fourth binary orbit and was consistent with zero pulsed flux thereafter. Only weak evidence was found for temporal variation in the pulsed flux between 33 and 98 keV. The pulsed spectrum has been fitted with a power law, a thermal spectrum without features, and a thermal spectrum with a superposed Gaussian centered at 55 keV. The latter fit has the smallest value of chi-square per degree of freedom, and the resulting integrated line intensity is approximately 0.0015 photon/sec per sq cm for a width of 3.1 (+9.1, -2.6) keV. This result, while of low statistical significance, agrees with the value observed by Truemper (1978) during the same ON-state.
Document ID
19790062014
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Maurer, G. S. (NASA Goddard Space Flight Center Greenbelt, Md.; Catholic University of America, Washington, D.C., United States)
Dennis, B. R. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Coe, M. J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Crannell, C. J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Dolan, J. F. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Frost, K. J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Orwig, L. E. (NASA Goddard Space Flight Center Greenbelt, Md., United States)
Cutler, E. P. (NASA Goddard Space Flight Center Greenbelt; Comtech, Lanham, Md., United States)
Date Acquired
August 9, 2013
Publication Date
August 1, 1979
Publication Information
Publication: Astrophysical Journal
Subject Category
ASTROPHYSICS
Funding Number(s)
CONTRACT_GRANT: NSG-5066
Distribution Limits
Public
Copyright
Other