The Swift Burst Alert Telescope (BAT)
Abstract
The Swift Gamma Ray Burst Explorer, to be launched in 2003, will observe hundreds of gamma ray bursts per year and study their X-ray and optical afterglow with its multiwavelength complement of three instruments: a large gamma ray telescope called the Burst Alert Telescope (BAT), an X-Ray Telescope (XRT), and a UV/Optical Telescope (UVOT). The BAT is a large coded aperture gamma ray telescope with a wide field-of-view that provides the gamma ray burst triggers for the Swift Mission. BAT will observe and locate hundreds of bursts per year to better than 4 arc minutes accuracy. Using this prompt burst location information, Swift can slew quickly (within 20 - 70 s) to point the on-board narrow field-of-view XRT and UVOT instruments at the burst for continued afterglow studies. The BAT instrument consists of a large (5200 cm2) hard x-ray detector plane positioned one meter away from an even larger (3.2 m2) coded aperture mask. The BAT detector plane consists of 256 CdZnTe semiconductor detector modules each containing 128 individual, planar 4 mm x 4 mm x 2 mm CdZnTe detectors that are read out by a single XA1 Application Specific Integrated Circuit (ASIC). The BAT mask will be constructed using 5 mm x 5 mm x 1 mm lead plates attached to a self-supporting 0.4 g/cm2 substrate fabricated from Kevlar fiber/honeycomb materials. With 4 mm square focal plane detector elements and 5 mm square mask pixels, BAT will have angular resolution better than 17 arc minutes and will determine GRB source locations to 4 arc minutes for bursts detected at 5 sigma or brighter. A full description of the BAT instrument and its capabilities will be presented along with results from performance tests of prototype detector modules. This work is funded by NASA's MIDEX program.
- Publication:
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American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1999
- Bibcode:
- 1999AAS...195.7102P