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Session 48 - Gamma Rays & X-ray Instrumentation.
Display session, Thursday, January 08
Exhibit Hall,
We have used the RXTE ASM to monitor 43 very small gamma-ray burst (GRB) error boxes for transient soft X-ray emission during the first year of operation. A number of GRB models have scenarios where repeated high energy events are possible. Currently the observational upper limit on the repeating fraction of GRBs is estimated to be < 5-20%. Monitoring archival GRB error boxes allows us to place direct limits on the repeating fraction. Previous soft x-ray studies of GRB error boxes have deeply imaged about one dozen error boxes for about 20 ksec each. No transient or quiescent objects were detected in those observations that could be identified as a potential GRB counterpart. Our study has accumulated > 21,500 ksec of monitoring of these 43 error boxes. The ASM single dwell flux limit on detecting flaring sources in the 2-12 keV bandpass is approximately 30 mcrab, while averaging all of the dwells over a single day can detect presistent sources as faint as 4 mcrab. We will report on the results from our monitoring program, and discuss the limitations our observations place on low-level transient behavior from GRB error boxes.
