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Circular No. 6209 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Postal Address: Central Bureau for Astronomical Telegrams Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science) Phone 617-495-7244/7440/7444 (for emergency use only) X-RAY NOVA 1994 IN SCORPIUS S. Sazonov and R. Sunyaev, on behalf of the GRANAT/WATCH Team, report: "GRO J1655-40 is very bright, according to GRANAT/WATCH in the spectral band 8-20 keV. After the bright outburst of late July-early Aug. (IAUC 6196, 6201, 6205), the source became relatively weak (250 +/- 100 mCrab) by Aug. 8. Since that date, its flux gradually increased to 800 +/- 200 mCrab on Aug. 16 and to 1400 +/- 100 mCrab on Aug. 19." S. N. Zhang, B. A. Harmon, W. S. Paciesas, and G. J. Fishman, Marshall Space Flight Center, NASA, report for the Compton Observatory BATSE Team: "The x-ray/radio transient source GRO J1655-40 has been undergoing another bright outburst in hard x-rays, immediately after the last outburst (IAUC 6196) reached a minimum flux level of about 60 mCrab (20-100 keV) on Aug. 9 (IAUC 6205). The energy spectrum can be well fitted by a power law with significant flux detectable up to 200 keV. The peak flux of the current outburst was 600 +/- 70 mCrab (20-100 keV) on Aug. 17. The flux has since declined to about 250 +/- 50 mCrab on Aug. 19. The photon spectral index changed from -2.1 on Aug. 10 to -2.5 on Aug. 17 and to -1.8 on Aug. 19, consistent with the spectral evolution seen previously from this source. We note that the 8- to 20-keV flux detected by WATCH/GRANAT continued to rise since Aug. 17 (see above). The current activity from July 22 appeared in phase with the previous three major outbursts with peak flux above 1 Crab, which were separated by 120 days." GRS 1915+105 Sazanov and Sunyaev also write: "The outburst of GRS 1915+105 detected by GRANAT/WATCH on 19 July (IAUC 6196) is still continuing as of Aug. 19. During the outburst, the source's flux at 8-20 keV has been about 700 mCrab with no significant variations in intensitydetected." Zhang et al. also report: "Hard x-ray activity from GRS 1915+105 has continued since a previous report (IAUC 6204). The flux in the band 20-100 keV peaked on Aug. 11 at 220 +/- 25 mCrab, following the intense radio flare on Aug. 10 (IAUC 6204), then decreased rapidly until the source was undetectable on Aug. 14. We note that the 8- to 20-keV flux (see above) continued to increase after Aug. 11, suggesting a hard-to-soft transition in the spectrum." 1995 August 21 (6209) Daniel W. E. Green
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