Abstract: view Abstract Citations (17) References (42) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Hard X-Ray Variability of NGC 4151 Perotti, F. ; Maggioli, P. ; Quadrini, E. ; Bazzano, A. ; Ubertini, P. ; Bassani, L. ; Stephen, J. B. ; Court, A. J. ; Dean, A. J. ; Dipper, N. A. ; Lewis, R. A. Abstract During a balloon flight on 1987 July 15 of the MIFRASO telescope, a region of the sky containing the Seyfert galaxy NGC 4151 was studied over the photon energy range 15-335 keV. A 13 α excess, interpreted as originating from the direction of NGC 4151, was detected in this energy band and the corresponding emission spectrum is represented by a single power law with a photon spectral index of α = 1.5 +/- 0.1. With respect to the 1986 July observation of this source with the same telescope, the {apha} slope is statistically unchanged while the X-ray flux in the energy range 27-80 keV shows, at the 95% confidence level, an increase of ~40%. An observation of the Crab Nebula, that proves the stability of the telescope response through the two measurements of NGC 4151, is also described. Publication: The Astrophysical Journal Pub Date: May 1991 DOI: 10.1086/170024 Bibcode: 1991ApJ...373...75P Keywords: Crab Nebula; Seyfert Galaxies; X Ray Spectra; Balloon-Borne Instruments; Emission Spectra; X Ray Astronomy; Astrophysics; GALAXIES: INDIVIDUAL NGC NUMBER: NGC 4151; GALAXIES: SEYFERT; GALAXIES: X-RAYS; NEBULAE: CRAB NEBULA full text sources ADS | data products SIMBAD (1) NED (1)
Publication Year: 1991
Publication Date: 1991-05-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 10
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