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L. M. Barbier, S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, C. Markwardt, R. Mushotsky, A. Parsons, T. Sakamoto, J. Tueller (NASA / GSFC), E. Fenimore, D. Palmer (LANL), G. Skinner (CESR, France), Swift-BAT Team
The Burst Alert Telescope (BAT) on the Swift satellite is a large field of view instrument that continually monitors the sky to provide the gamma-ray burst trigger for Swift. An average of more than 70% of the sky is observed on a daily basis. The survey mode data is processed on two sets of time scales: from one minute to one day as part of the transient monitor program, and from one spacecraft pointing (~20 minutes) to the full mission duration for the hard X-ray survey program.
In the transient monitor program, sky images are processed to detect astrophysical sources in six energy bands covering 15-350 keV. The detected flux or upper limit in each energy band is calculated for >300 objects on time scales up to one day. In addition, the monitor is sensitive to an outburst from a new or unknown source. Sensitivity as a function of time scale for catalog and unknown sources will be presented. The daily exposure for a typical source is ~1500 - 3000 seconds, with a 1-sigma sensitivity of ~4mCrab. 90% of the sources are sampled at least every 16 days, but many sources are sampled daily. The BAT team will soon make the results of the transient monitor public to the astrophysical community through the Swift mission web page. It is expected that the Swift-BAT transient monitor will become an important resource for the high energy astrophysics community.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.