TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2898 SUBJECT: GRB041223: Swift-BAT detection of a bright long burst DATE: 04/12/23 17:58:52 GMT FROM: Scott Barthelmy at NASA/GSFC J. Tueller, L. Barbier, S. Barthelmy (GSFC), A. Beardmore (U.Leicester), L. Cominsky (Sonoma State U), J. Cummings (GSFC), E. Fenimore (LANL), N. Gehrels (GSFC), S.T. Holland (GSFC/USRA), D. Hullinger (GSFC/UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean, D. Palmer (LANL), A. Parsons (GSFC), G. Sato (ISAS), M. Suzuki (Saitama), G. Tagliaferri (OAB) on behalf of the Swift BAT team: At 14:06:18 UT, the Swift Burst Alert Telescope (BAT) triggered and located on-board GRB041223. The spacecraft did not autonomously slew to the burst since automated slewing was not yet enabled. The BAT ground-calculated location is RA,Dec 100.183,-37.066 (J2000) with an uncertainty of 7 arcmin (radius, 3-sigma, including systematic uncertainty using a preliminary bore-sight alignment calibration). This is 27 degrees off the BAT bore sight and was in the partially encoded field of view. The burst lightcurve is multi-peaked with structure within the peaks with the main emission lasting ~60 sec. The peak flux was 7.5 events/cm^2/sec (1-sec sampling; unsaturated; ~15 to 100 keV; ~28 Crab). The total duration was ~130 sec. The fluence was ~2e-5erg/cm^2. A reduced energy band is being quoted because of our response uncertainty in the >100 keV band, and because of strong emission by this burst in this band.