TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2883 SUBJECT: GRB041219b: A Swift-BAT burst DATE: 04/12/20 07:37:08 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift J. Cummings, L. Barbier, S. Barthelmy (GSFC), M. Chester (PSU), E. Fenimore (LANL), N. Gehrels (GSFC), P. Giommi (ASDC), M. Goad (U.Leicester), D. Hullinger (UMD), K. Hurley (UCB), H. Krimm (USRA), C. Markwardt (UMD), K. McLean (LANL), D. Palmer (LANL), A. Parsons (GSFC), G. Sato (ISAS), M. Suzuki (Saitama), J. Tueller (GSFC) on behalf of the Swift BAT team. At 15:38:48 UT, the Swift Burst Alert Telescope (BAT) triggered and located on-board GRB041219b. The spacecraft did not autonomously slew to the burst since automated slewing is not yet enabled. Automated notification through TDRSS is also disabled during this early commissioning phase of the mission. The ground-calculated location is RA,Dec 167.674,-33.458 (J2000) with an uncertainty of 12 arcmin (radius, including a large systematic uncertainty due to the lack of an on-orbit bore-sight alignment calibration). This is ~25 degrees off the BAT bore sight and is ~90% encoded. It was a 82 sigma detection. The burst lightcurve has one strong peak (width ~5 sec) of 10 events/cm^2/sec in the ~15 to 200 keV band. It is preceded by one small peak and followed by two small peaks. The total duration was 30 sec.