GCN Circular 42636

Subject

GRB 251103B: Swift-BAT refined analysis

Event

GRB 251103B

Date

2025-11-11T05:05:46Z (21 hours ago)

From

Mike Moss at NASA GSFC <mikejmoss3@gmail.com>

Via

Web form

R. Gupta (GSFC), S. D. Barthelmy (GSFC), 
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
S. Lanava (PSU), 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-240 to T+1282 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 251103B (trigger #1409824)
(Lanava, et al., GCN Circ. 42556Loading...
 
 ).  The BAT ground-calculated position is
RA, Dec = 105.870, -24.871 deg which is 
   RA(J2000)  =  07h 03m 28.7s 
   Dec(J2000) = -24d 52' 14.9" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 99%.
 
The mask-weighted light curve displays a complicated structure with tens of pulses.
Significant emission begins at ~T0-110 seconds and ends ~T0+95 seconds. 
T90 (15-350 keV) is 127.86 +- 22.41 sec (estimated error including systematics).
 
The time-averaged spectrum from T-52.07 to T+92.74 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.79 +- 0.08.  The fluence in the 15-150 keV band is 3.5 +- 0.1 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+2.00 sec in the 15-150 keV band
is 2.9 +- 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/1409824