Abstract During a balloon flight in July 1987 of the MIFRASO hard X-ray telescope, a single drift-scan observation was performed to survey a region of the sky containing the galactic black hole candidate Cyg X−1. In about 900 seconds of on-source useful data, Cyg X−1 was detected in the energy range 15–300 keV with a high degree of statistical significance. The photon spectrum is well described by either a single power law with a photon index of α = 1.9 ± 0.07 or a Comptonized model characterized by an electron temperature of kT = 56 ± 9 keV and an optical depth of τ = 2.3 ± 0.3. The measured flux values suggest that during the MIFRASO observation the source was in the so called ‘superlow’ state.


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    Title :

    Hard X-ray observations of Cygnus X−1 with the Mifraso telescope


    Contributors:
    Perotti, F. (author) / Bassani, L. (author) / Bazzano, A. (author) / Court, A. (author) / Dean, A.J. (author) / Dipper, N. (author) / Lewis, R. (author) / Quadrini, E. (author) / Stephen, J.B. (author) / Ubertini, P. (author)

    Published in:

    Advances in Space Research ; 11 , 8 ; 101-105


    Publication date :

    1991-01-01


    Size :

    5 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English



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