GCN Circular 41748

Subject

GRB 250905A: Swift-BAT refined analysis

Event

GRB 250905A

Date

2025-09-08T15:16:06Z (a month ago)

From

D. R. Sadaula at NASA GSFC <dev.r.sadaula@nasa.gov>

Via

Web form

T. Parsotan (GSFC), S. D. Barthelmy (GSFC), 
R. Gupta (GSFC), 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), 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 250905A (trigger #1347265)
(Brivio, et al., GCN Circ. 41714Loading...
 
 ).  The BAT ground-calculated position is
RA, Dec = 232.943, 0.789 deg which is 
   RA(J2000)  =  15h 31m 46.3s 
   Dec(J2000) = +00d 47' 19.6" 
with an uncertainty of 3.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 74%.
 
The BAT light curve showed a complex structure with multiple peaks. The burst lasted about 70 sec. T90 (15-350 keV) is 48.00 +- 50.60 sec (estimated error including systematics).
 
The time-averaged spectrum from T-15.10 to T+64.89 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.65 +- 0.67.  The fluence in the 15-150 keV band is 4.1 +- 1.4 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+8.40 sec in the 15-150 keV band
is 0.27 +- 0.16 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/1347265