TITLE: GCN CIRCULAR NUMBER: 39147 SUBJECT: GRB 250129A: Swift-BAT refined analysis DATE: 25/02/04 20:36:28 GMT FROM: Rahul Gupta at NASA GSFC rahul.gupta@nasa.gov
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), 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-571 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250129A (trigger #1285812) (Beardmore, et al., GCN Circ. 39066). The BAT ground-calculated position is RA, Dec = 198.708, 5.029 deg which is RA(J2000) = 13h 14m 49.8s Dec(J2000) = +05d 01' 44.9" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 84%.
The mask-weighted BAT light curve exhibits a multi-peaked and complex structure, with the most prominent peak occurring at approximately T0 + 184 seconds. T90 (15-350 keV) is 262.25 +- 23.71 sec (estimated error including systematics).
The time-averaged spectrum from T-64.39 to T+302.62 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.17 +- 0.09. The fluence in the 15-150 keV band is 5.0 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+184.12 sec in the 15-150 keV band is 1.4 +- 0.2 ph/cm2/sec. 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/1285812
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