TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3005 SUBJECT: GRB 050202: Short burst detected by Swift-BAT DATE: 05/02/02 05:16:55 GMT FROM: Craig Markwardt at NASA/GSFC/UMD J. Tueller (GSFC), L. Antonelli (INAF-OAR), S. Barthelmy, L. Barbier (GSFC), D. Burrows (PSU), J. Cummings (GSFC), E. Fenimore (LANL), N. Gehrels, K. Gendreau (GSFC), D. Hullinger (GSFC/UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean (LANL), J. Nousek (PSU), D. Palmer (LANL), A. Parsons (GSFC), S. Piranmonte (ASDC), T. Sakamoto (GSFC), G. Sato (ISAS), M. Suzuki (Saitama), A. Wells (Leicester) on behalf of the Swift-BAT team: Swift-BAT detected a burst at 03:35:14.79 UT. The BAT on-board calculated location is RA,Dec 290.560, -38.720 (J2000) with an uncertainty of 4 arcmin (radius, 3-sigma, including a systematic uncertainty). This appears to be a short burst (single spike, duration of ~400 msec), dominated by emission in the 25-100 keV band. The peak rate is approximately 3000 ct/s. However, there are some longer-term variations (~150 sec) in the lowest energy band (15-25 keV). These could be due to (a) magnetospheric variations, (b) variations of the galactic sources in the field of view, or (c) intrinsic GRB variations. When more complete data is available, we should be able to remove this ambiguity.