The USA Experiment is an X-ray timing experiment with large collecting area and microsecond time resolution, capable of conducting a broad program of studies of galactic X-ray sources. It is one of nine experiments aboard the Advanced Research and Global Observation Satellite which was launched February 23, 1999. USA is a collimated proportional counter X-ray telescope with about 1000 cm2 of effective area per detector with two detectors, sensitive to photons in the energy range 1-15 keV. USA is investigating phenomena such as kHz QPOs recently discovered in some X-ray binaries, coherent millisecond periodicities in X-ray bursts, rapid variability in black hole systems, precise absolute timing of both rotation and accretion powered X-ray pulsars, and other topics. Substantial observing time has been obtained on Cyg X-1, PSR B1509-58, Aql X-1, Cen X-3, X1630-472, Cyg X-2, X1636-536, GX 1+4, 1E2259+586, X1820-30, X1630-472, 1E1048.1-5937, GRS1915+105, and Cas A, among others. We will present an overview of the USA status, capabilities and scientific observing plan as well as preliminary results from early science observations.
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1999