Pottschmidt, KatjaWilms, J.Chernyakova, M.Nowak, M. A.Rodriguez, J.Zdziarski, A. A.Beckmann, V.Kretschmar, P.Gleissner, T.Pooley, G. G.Martínez-Núñez, S.Courvoisier, T. J.-L.Schönfelder, V.Staubert, R.2023-10-122023-10-122003-11-17Pottschmidt, K., J. Wilms, M. Chernyakova, M. A. Nowak, J. Rodriguez, A. A. Zdziarski, V. Beckmann, et al. “INTEGRAL-RXTE Observations of Cygnus X-1.” Astronomy & Astrophysics 411, no. 1 (November 1, 2003): L383–88. https://doi.org/10.1051/0004-6361:20031258.https://doi.org/10.1051/0004-6361:20031258http://hdl.handle.net/11603/30127We present first results from contemporaneous observations of Cygnus X-1 with INTEGRAL and RXTE, made during INTEGRAL’s performance verification phase in 2002 November and December. Consistent with earlier results, the 3−250 keV data are well described by Comptonization spectra from a Compton corona with a temperature of kT ∼ 50−90 keV and an optical depth of τ ∼ 1.0−1.3 plus reflection from a cold or mildly ionized slab with a covering factor of Ω/2π ∼ 0.2−0.3. A soft excess below 10 keV, interpreted as emission from the accretion disk, is seen to decrease during the 1.5 months spanned by our observations. Our results indicate a remarkable consistency among the independently calibrated detectors, with the remaining issues being mainly related to the flux calibration of INTEGRAL.6 pagesen-USThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.Attribution 4.0 International (CC BY 4.0)https://creativecommons.org/licenses/by/4.0/Text