TITLE: GCN CIRCULAR NUMBER: 32496 SUBJECT: GRB 220826A: Swift-BAT refined analysis DATE: 22/08/27 19:50:26 GMT FROM: Amy Lien at GSFC amy.y.lien@nasa.gov
T. Sakamoto (AGU), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC), R. Caputo (GSFC), M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 220826A (trigger #1121751) (Caputo et al., GCN Circ. 32484). The BAT ground-calculated position is RA, Dec = 206.421, -44.036 deg which is RA(J2000) = 13h 45m 41.0s Dec(J2000) = -44d 02' 10.1" with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 92%.
The mask-weighted light curve shows a multi-peaked structure that starts at ~T0 and ends at ~T+13 s. There are roughly three main peaks at ~T+1 s, ~T+7 s, and ~T+11 s. respectively. T90 (15-350 keV) is 11.14 +- 1.02 sec (estimated error including systematics).
The time-averaged spectrum from T-0.20 to T+13.01 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.44 +- 0.10. The fluence in the 15-150 keV band is 1.2 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+6.58 sec in the 15-150 keV band is 2.6 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/1121751/BA/