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The Ophiuchus cluster - A bright X-ray cluster of galaxies at low galactic latitudeThe discovery of an extended X-ray source identified with a cluster of galaxies at low galactic latitude is reported. The source, designated the Ophiuchus cluster, was detected near 4U 1708-23 with the HEAO 1 Scanning Modulation Collimator, and identified with the cluster on the basis of extended X-ray size and positional coincidence on the ESO/SRC (J) plate of the region. An X-ray flux density in the region 2-10 keV of approximately 25 microJ was measured, along with an X-ray luminosity of 1.6 x 10 to the 45th ergs/sec and an X-ray core radius of approximately 4 arcmin (0.2 Mpc) for an assumed isothermal sphere surface brightness distribution. The X-ray spectrum in the range 2-10 keV obtained with the HEAO 1 A-2 instrument is well fit by a thermal bremsstrahlung model with kT = 8 keV and a 6.7-keV iron line of equivalent width 450 eV. The steep-spectrum radio source MSH 17-203 also appears to be associated with the cluster, which is the closest and brightest representative of the class of X-ray clusters with a dominant central galaxy.
Document ID
19810050472
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Johnston, M. D.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Bradt, H. V.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Doxsey, R. E.
(MIT Cambridge, Mass., United States)
Marshall, F. E.
(NASA Goddard Space Flight Center Greenbelt, Md., United States)
Schwartz, D. A.
(Harvard-Smithsonian Center for Astrophysics Cambridge, Mass., United States)
Margon, B.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Date Acquired
August 11, 2013
Publication Date
May 1, 1981
Publication Information
Publication: Astrophysical Journal
Subject Category
Astronomy
Accession Number
81A34876
Funding Number(s)
CONTRACT_GRANT: NAS8-30543
CONTRACT_GRANT: NAS8-27972
CONTRACT_GRANT: NSF AST-77-27745
Distribution Limits
Public
Copyright
Other

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