2 ASM burst detections

The RXTE/ASM has detected and positioned 14 GRB since Feb. 1996. Each of the 14 has been confirmed as a burst with detections from GRB detectors on one or more other satellites. Seven of these were detected in two of the ASM shadow cameras, thus yielding positions accurate to a few arcmintues in two dimensions. Of the 14, eight were located in searches of archived data. One of these (GRB 961216) was near the edge of the ASM camera field of view and thus led to a large (and uncertain) error region. The other 7 archival detections and positions are reported in Smith et al. (1999) together with detections and positions of these events from other satellites. They are GRB 960416, 960529, 960727, 961002, 961019, 961029, and 961230.

  

Figure: ASM Positions of the six bursts reported in near real time by the ASM group together with refined BATSE and Interplanetary Network positions from other groups as reported or referenced in Smith et al. (1999)

Beginning in August 1997, bursts detected by the ASM were analyzed and positions were reported in near real time. Six events have been so reported at times ranging from 2 to 32 hours after the burst. The error regions reported by us and by others for these six bursts are shown in Fig. 1. Notable among these are (1) GRB 970828 (Remillard et al. 1997) which had an easily detected X-ray afterglow but no optical or radio signal (Groot et al. 1998), (2) GRB 980703 (Levine et al. 1998) which led to a radio/optical transient with a redshift z = 0.9660 (Djorgovski et al. 1998), and (3) GRB 981220 (Smith 1998b) which led to the discovery of a highly variable radio source as a possible counterpart candidate (Galama et al. 1998; Frail & Kulkarni 1998). The radio source was associated with a faint galaxy at R = 26.4 (Bloom et al. 1999). The GRB 971214 led to a redshift of z = 3.42 but this result came primarily through the precise two-dimensional positions from SAX (Heise et al. 1997; Antonelli et al. 1997). The ASM results and associated studies are reported or referenced in Smith et al. (1999).