TITLE: GCN CIRCULAR NUMBER: 38876 SUBJECT: GRB 250108B: Swift-BAT refined analysis DATE: 25/01/09 16:42:39 GMT FROM: Rahul Gupta at NASA GSFC rahul.gupta@nasa.gov
S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), R. Gupta (GSFC), N. J. Klingler (GSFC/UMBC/CRESSTII), H. A. Krimm (NSF), 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-239 to T+792 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250108B (trigger #1280056) (Klinger et al., GCN Circ. 38847). The BAT ground-calculated position is RA, Dec = 201.312, 25.622 deg which is RA(J2000) = 13h 25m 14.8s Dec(J2000) = +25d 37' 19.4" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 89%.
The mask-weighted light curve exhibits multi-peaked structures, including evidence of precursor emission prior to the main burst. T90 (15-350 keV) is 229.66 +- 43.30 sec (estimated error including systematics).
The time-averaged spectrum from T-63.14 to T+218.21 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.63 +- 0.19. The fluence in the 15-150 keV band is 1.7 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+1.56 sec in the 15-150 keV band is 0.6 +- 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/1280056
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