TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3162 SUBJECT: Swift-BAT detection of GRB 050401 DATE: 05/04/01 15:25:21 GMT FROM: Louis M Barbier at NASA/GSFC/Swift L. Barbier (GSFC), S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), J. Norris (GSFC), J. Nousek (PSU), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), M. Suzuki (Saitama), J. Tueller (GSFC) on behalf of the Swift team: At 14:20:15 UT Swift-BAT triggered on burst GRB 050401 (trigger=113120). The BAT-derived position is RA,Dec=247.880,+2.184 (J2000). We note this is 42 arcsec from the XRT Position GCN Notice. The lightcurve shows 5 main peaks with a total burst duration of 38 sec. The first peak started about 9 sec before the trigger, and the fifth peak started at T+23 sec. The peak count rate was 5000 cnts/sec. This burst was 56 deg of the BAT bore sight (<10% coding). We note that the Swift Star Trackers were locked at the time of the trigger and all initial inspections indicate that the attitude solution for the s/c is normal (unlike yesterday's episode).