TITLE: GCN CIRCULAR NUMBER: 37084 SUBJECT: GRB 240805B: Swift-BAT refined analysis DATE: 24/08/06 20:26:19 GMT FROM: Rahul Gupta at NASA GSFC rahul.gupta@nasa.gov
H. A. Krimm (NSF), S. D. Barthelmy (GSFC), R. Gupta (GSFC), 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-239 to T+1121 sec from the recent telemetry downlink, we report further analysis of BAT GRB 240805B (trigger #1246989) (Williams, et al., GCN Circ. 37043). The BAT ground-calculated position is RA, Dec = 254.215, 18.314 deg which is RA(J2000) = 16h 56m 51.5s Dec(J2000) = +18d 18' 49.9" with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 85%.
The mask-weighted BAT light curve shows a complex structure with a duration of ~ 100 sec. T90 (15-350 keV) is 64.99 +- 2.56 sec (estimated error including systematics).
The time-averaged spectrum from T-0.76 to T+96.68 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.07 +- 0.26, and Epeak of 72.1 +- 12.0 keV (chi squared 38.84 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 4.5 +- 0.2 x 10^-06 erg/cm2 and the 1-sec peak flux measured from T+15.95 sec in the 15-150 keV band is 2.4 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.71 +- 0.06 (chi squared 59.87 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/1246989
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