GRIS: High Resolution Gamma-Ray Spectroscopy of Cyg X-1

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Session 29 -- Gamma Ray Astrophysics
Oral presentation, Wednesday, January 12, 2:15-3:45, Salon III Room (Crystal Gateway)

[29.02] GRIS: High Resolution Gamma-Ray Spectroscopy of Cyg X-1

J. Tueller, S. D. Barthelmy, N. Gehrels, B. J. Teegarden (NASA/GSFC), L. M. Bartlett and M. Leventhal (UMd at College Park)

The Gamma-Ray Imaging Spectrometer (GRIS)was flown on a high=20 altitude balloon from Ft Sumner, NM on 24 September 1993. During= =20 a 20 hour flight, GRIS made high-resolution observations of=20 NGC 4151, Cyg X-1, and the Crab Nebula with a cooled germanium=20 spectrometer (about 2 keV FWHM resolution). The heavy active=20 shielding was supplemented by a passive fine collimator, which=20 reduced the normal 18 degree FOV to 6 degrees and produced=20 significantly improved hard x-ray sensitivity. Preliminary analysis= =20 indicates that GRIS was operating normally in-flight, and continuum= =20 emission is clearly detected. Results from our observation of Cyg= X-1,=20 including continuum measurements and a search for gamma-ray lines,= =20 will be presented.

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