HEAD Division Meeting 1999, April 1999
Session 37. Missions
Oral, Thursday, April 15, 1999, 11:00am-12:40pm, Colonial Room

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[37.01] Initial Results from the USA Experiment on ARGOS

K.S. Wood, G. Fritz, P.L. Hertz, W.N. Johnson, M.N. Lovellette, P.S. Ray, M.T. Wolff (NRL), R. Bandyopadhyay (NRC/NRL), E.D. Bloom, C. Chaput, G. Godfrey, P. Saz Parkinson, G. Shabad (SLAC), P. Michelson, M. Roberts (Stanford), D.A. Leahy (Calgary), L. Cominsky (Sonoma State), J. Scargle (NASA Ames), J. Beall (SJC), D. Chakrabarty (MIT), Y. Kim (Saddleback College)

The USA Experiment is a new X-ray timing experiment with large collecting area and microsecond time resolution, capable of conducting a broad program of studies of galactic X-ray binaries. USA is one of nine experiments aboard the Advanced Research and Global Observation Satellite (ARGOS) which is scheduled to be launched aboard a Boeing Delta II rocket in February, 1999. USA is expected to be powered on and initialized in late March, 1999. USA is a collimated proportional counter X-ray telescope with about 2000 cm2 of effective area and is sensitive to photons in the energy range 1--15 keV. A unique feature of USA is that all photon events are time tagged by reference to an onboard GPS receiver allowing precise absolute time and location determination. USA will investigate phemomena 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. We will present an overview of the USA capabilities and scientific observing plan as well as the current status of the instrument and some selected initial results.

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