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[35.01] The Variable X-ray Sky from the All-Sky Monitor on RXTE

H. V. D. Bradt (MIT)

The All-Sky Monitor (ASM) on the Rossi X-ray Timing Explorer (RXTE, launched 12/30/95) is currently monitoring 327 objects for x-ray emission (1.5-12 keV) with a threshold of ~10 milliCrab (mC) in one day. Detectable fluxes greater than 15 mC have been detected from 148 of these objects on at least some occasion, and another 30 objects are detected in the range 2 - 30 mC in long-term averages of up to 6 months. The result is a unique data set consisting of light curves in 3 energy channels that will extend for about 4 years at the time of this meeting. In near real time, the data have made possible the optimum use of the pointed instruments on RXTE and other observatories for the study of transient states of previously known and newly discovered x-ray sources. These sources include neutron-star and black-hole binary `transients' that recur with repeatable timescales, binaries with precessing accretion disks, radio-jet (galactic) `microquasars,' and a few nearby BL Lac objects (TeV emitters). After the fact, the light curves provide context for the state of sources at the times of short pointed observations. Finally, the light curves themselves provide signatures against which theories of accretion processes can be tested. A 4-year animation of the X-ray sky will be presented.