TITLE: GCN CIRCULAR NUMBER: 38721 SUBJECT: GRB 241229B: Swift-BAT refined analysis DATE: 24/12/30 05:50:24 GMT FROM: Amy <yarleen@gmail.com> S. D. Barthelmy (GSFC), D'Ai (INAF-IASFPA), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 241229B (trigger #1277428) (D'Ai et al., GCN Circ. 38699). The BAT ground-calculated position is RA, Dec = 274.140, 74.694 deg which is RA(J2000) = 18h 16m 33.5s Dec(J2000) = +74d 41' 39.5" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 39%. The mask-weighted light curve shows several overlapping pulses that start at ~T-3 s and end at ~T+3 s. The main peak occurs at ~T+0.5 s, T90 (15-350 keV) is 5.05 +- 0.65 sec (estimated error including systematics). The time-averaged spectrum from T-2.62 to T+3.38 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.93 +- 0.50, and Epeak of 68.3 +- 22.6 keV (chi squared 47.78 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 7.0 +- 0.6 x 10^-07 erg/cm2 and the 1-sec peak flux measured from T-0.06 sec in the 15-150 keV band is 4.0 +- 0.3 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.70 +- 0.11 (chi squared 55.86 for 57 d.o.f.). All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1277428 View this GCN Circular online at https://gcn.nasa.gov/circulars/38721. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...