SUMMARY OF PROPOSAL 42066 DR. BERNARD F. PHLIPS NAVAL RESEARCH LABORATORY DC USA 20375 WASHINGTON 4555 OVERLOOK AVENUE SW E-mail: PHLIPS@OSSE.NRL.NAVY.MIL Tel: (202)767-3572 Fax: (202)767-6473 Medium: 4GBDAT Subject: X-RAY BINARIES Title: A BROAD-BAND OBSERVATION OF CYGNUS X-1 WITH ASCA, XTE AND CGRO Abstract: 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. Co-Is: 1 KEN EBISAWA ASCA GOF/USRA USA EBISAWA@SUBARU.GSFC.NASA.GOV 301-286-1586 2 YOSHI UEDA ISAS JAPAN 3 ERIC GROVE NRL USA 4 NEIL JOHNSON NRL USA 5 ANDRE ZDZIARSKI N COPERNICUS CENTER POLAND Target Name PRI RA Dec Time TC Off GIS SIS_Cts Obs ------------------- --- -------- -------- ---- -- --- --- ------- --- CYG X-1 0 299.5900 35.2017 80 Y Y P 200.00000 4 REMARKS: WE REQUEST FOUR SUCCESSIVE OBSERVATIONS CENTERING AT ORBITAL PHASE 0.0,0.25, 0.5 AND 0.75 BETWEEN MARCH 20 AND APRIL 1 1996. THE PHASE ZERO OCCURS AT MAR 19 19:53, MAR 25 10:17 AND MAR 31 00:41. Co-Ordinated Ob: Start: Mar 20, 96 at 00 UT Stop: Apr 1, 96 at 2359 UT Monitored Oservation: Min. Int: 121.000 Max. Int: 121.000 Phase Critical Oservation: Epoch: 48989.1738 Period: 5.60000000 Min: 0.0000 Max: 0.7500