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Session 43 - Gamma-ray Burst Counterparts and Afterglows.
Display session, Tuesday, June 09
Atlas Ballroom,
We have used the ROSAT HRI to observe four small gamma-ray burst (GRB) error boxes obtained by the IPN. The sizes of the error boxes range from 3.6 to 27 square arcmin. The effective exposure times for each target varied from about 16 ks to about 23 ks. We have not found any sources inside any of the four GRB error boxes. The 3 sigma upper limits are estimated assuming a source temperature of 1 keV, and a neutral hydrogen column density of 10^22 cm^-2 toward the source. The results are around 4.0x10^-13 erg cm^-2 s^-1 for thermal bremsstrahlung radiation, and around 2.0x10^-13 erg cm^-2 s^-1 for black body radiation. The probability of detecting a source within a given error box is estimated to range from 8.36x10^-3 to 1.29x10^-1. We use this wide range of parameters to constrain the physical nature of GRB hosts assuming that they are extragalactic.
