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An Observation of the Galactic Center Hard X-Ray Source, 1E 1740.7-2942, with the Caltech Coded-Aperture Telescope

Heindl, William A. and Cook, W. R. and Grunsfeld, J. M. and Palmer, D. M. and Prince, Thomas A. and Schindler, S. M. and Stone, E. C. (1993) An Observation of the Galactic Center Hard X-Ray Source, 1E 1740.7-2942, with the Caltech Coded-Aperture Telescope. Astrophysical Journal, 408 (2). pp. 507-513. ISSN 0004-637X. doi:10.1086/172608.

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The Galactic center region hard X-ray source 1E 1740.7-2942 has been observed with the Caltech Gamma-Ray Imaging Payload (GRIP) from Alice Springs, Australia, on 1988 April 12 and on 1989 April 3 and 4. We report here results from the 1989 measurements based on 14 hr of observation of the Galactic center region. The observations showed lE 1740.7 -2942 to be in its normal state, having a spectrum between 35 and 200 keV characterized by a power law with an exponent of -2.2 ± 0.3 and flux at 100 keV of (7.0 ± 0.7) x 10^(-s) cm^(-2) s^(-1) kev^(-1). No flux was detected above 200 keV. A search for time variability in the spectrum of lE 1740.7-2942 on one hour time scales showed no evidence for variability.

Item Type:Article
Related URLs:
URLURL TypeDescription Technical Reports Server (NTRS)
Prince, Thomas A.0000-0002-8850-3627
Stone, E. C.0000-0002-2010-5462
Additional Information:© American Astronomical Society. Provided by the NASA Astrophysics Data System. We acknowledge the important contributions to the development of the GRIP telescope made by W. Althouse, D. Burke, A. Cummings, M. Finger, C. Starr, J. Weger, and the personnel of the Central Engineering Services at Caltech. We thank the personnel of the National Scientific Balloon Facility and the NASA Wallops Flight Facility for their excellent balloon launch support. This work was supported in part by NASA grant NAGW-1919. W. Heindl is supported under the NASA GSRP, NGT-50804.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Subject Keywords:Galaxy: center - gamma rays: observations - X-rays: interstellar
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory1993-02
Issue or Number:2
Record Number:CaltechAUTHORS:20140516-102225572
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:45796
Deposited By: Deborah Miles
Deposited On:20 May 2014 18:33
Last Modified:10 Nov 2021 17:16

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