TITLE:   GCN CIRCULAR
NUMBER:  45733
SUBJECT: GRB 260924A: Swift-BAT refined analysis
DATE:    26/09/24 21:08:37 GMT
FROM:    Amy <yarleen@gmail.com>

R. Gupta (GSFC), S. D. Barthelmy (GSFC), V. D'Elia (SSDC & INAF-OAR), 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-180 to T+712 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 260924A (trigger #1513082)
(D'Elia et al., GCN Circ. 45713).  The BAT ground-calculated position is
RA, Dec = 133.754, 12.041 deg which is
   RA(J2000)  =  08h 55m 00.9s
   Dec(J2000) = +12d 02' 27.0"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The
partial coding was 39%.

The mask-weighted light curve shows a bright multi-peaked structure that
starts at ~T-10 s and ends at ~T+450 s. There are roughly two distinct
structures. The first structure starts at ~T-10 s and ends at ~T+160 s and
consists of many overlapping pulses. The second structure is a single
FRED-like pulse and starts at ~T+330 s, peaked at ~T+340 s, and ends at
~T+400 s. T90 (15-350 keV) is 344.82 +- 1.78 sec (estimated error including
systematics).

The time-averaged spectrum from T-5.96 to T+455.68 sec is best fit by a
simple power-law model.  The power law index of the time-averaged spectrum
is 1.24 +- 0.02.  The fluence in the 15-150 keV band is 5.7 +- 0.1 x 10^-05
erg/cm2. The 1-sec peak photon flux measured from T+338.78 sec in the
15-150 keV band is 10.5 +- 0.4 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/1513082