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   PR # 42066
   We propose observations of the black hole candidate Cygnus X-1 with
   ASCA that would be contemporaneous with already approved XTE and CGRO
   observations. By acquiring simultaneous spectra over the X- and
   gamma-ray bands, a unique data set would be available to test models
   such as disk reflection by covering both the reflection peak and the
   narrow Fe line. Thermal Comptonization models would be tested since
   the spectral coverage will extend from 0.5 keV (the seed photons) to
   a few MeV, beyond the break of Comptonization. The underlying
   continuum would be determined by the matching XTE observation and
   would allow for the study of possible redshifted Fe lines. The
   observations would be four 20 ks viewings, spaced over the 5.6 day
   orbital period, mapping the orbital change in the Fe line flux.
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