X-Ray Novae

A. Kaniovsky, K. Borozdin, and R. Sunyaev, on behalf of the Mir-Kvant team, report: "The soft x-ray transient GRS 1009-45, discovered by Granat/WATCH and more precisely localized by BATSE (IAUC 5864), was observed by the TTM and HEXE instruments of Mir-Kvant on Sept. 30. Preliminary analysis shows that the source spectrum in the band 2-200 keV is similar to the spectra of the x-ray novae QZ Vul = GS 2000+25 and GU Mus (= Nova Mus 1991) = GRS 1124-684. A bright, soft component can be approximated by a black-body spectrum with a temperature of 0.52 +/- 0.03 keV. The source spectrum at the higher energies 10-100 keV is well approximated by a power law with spectral index -2.53 +/- 0.05. The flux from the source at 3 and 20 keV was equal to 1 and 0.1 Crab unit, respectively." K. Borozdin, V. Arefiev, and R. Sunyaev, on behalf of the Mir- Kvant-TTM team, report: "Mir-Kvant observed the hard x-ray transient GRS 1716-249 = GRO J1719-24 and found that the source spectrum in the band 2-27 keV is approximated by a single power law with spectral index -1.57 +/- 0.13. No trails of the soft component were detected in the spectrum; it is reminiscent of the spectra of V1357 Cyg = Cygnus X-1, 1E 1740.7-2942, and the x-ray novae V404 Cyg = GS 2023+338 and GRO J0422+32. The flux was continuously growing, from 200 mCrab on Sept. 26 and 550 mCrab on Sept. 27 up to 750 mCrab on Oct. 3 in the band 12-17 keV."