GCN Circular 42103

Subject

GRB 251003A: Swift-BAT refined analysis

Event

GRB 251003A

Date

2025-10-04T00:52:50Z (5 days ago)

From

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

Via

Web form

S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), 
A. P. Beardmore (U Leicester), R. Gupta (GSFC),
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+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 251003A (trigger #1400964)
(Beardmore, et al., GCN Circ. 42070Loading...
 
 ).  The BAT ground-calculated position is
RA, Dec = 18.495, 56.483 deg which is 
   RA(J2000)  =  01h 13m 58.7s 
   Dec(J2000) = +56d 28' 57.1" 
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 97%.
 
The mask-weighted light curve displays a single fast-rise exponential decay pulse
lasting between ~T0-2 sec and ~T0+10 seconds. T90 (15-350 keV) is 10.78 +- 2.35 sec 
(estimated error including systematics).
 
The time-averaged spectrum from T-2.41 to T+9.80 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.64 +- 0.15.  The fluence in the 15-150 keV band is 4.1 +- 0.4 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+0.92 sec in the 15-150 keV band
is 1.0 +- 0.1 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/1400964