A balloon-borne coded-aperture telescope, measuring gamma-ray photons in the 160 keV to 9.3 MeV range, was used to observe the Cygnus region of the sky on October 1 and 2, 1984. In the 2-9.3-MeV band, evidence is found for a hard spectral component with a mean flux level at the top of the atmosphere of 7.4 + or - 2.5 x 10 to the -7th photons/sq cm per s per keV, inconsistent with the predictions of the inverse Compton models normally used to describe the X-ray emission. Both Cyg X-1 and Cyg X-3 could be observed simultaneously with the telescope. The results are used to establish 1-sigma upper flux limits on the spectral emission from Cyg X-3.
American Astronomical Society
Digital Object Identifier (DOI)
M.L. McConnell, D.J. Forrest, A. Owens, P.P. Dunphy, W.T. Vestrand, and E.L. Chupp, Gamma-ray observations of Cygnus X-1 and Cygnus X-3 using a coded-aperture telescope, 1989, Ap. J., v. 343, pp. 317-322