TITLE:   GCN CIRCULAR
NUMBER:  38876
SUBJECT: GRB 250108B: Swift-BAT refined analysis
DATE:    25/01/09 16:42:39 GMT
FROM:    Rahul Gupta at NASA GSFC <rahul.gupta@nasa.gov>

S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), 
R. Gupta (GSFC), N. J. Klingler (GSFC/UMBC/CRESSTII),
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+792 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 250108B (trigger #1280056)
(Klinger et al., GCN Circ. 38847).  The BAT ground-calculated position is
RA, Dec = 201.312, 25.622 deg which is 
   RA(J2000)  =  13h 25m 14.8s 
   Dec(J2000) = +25d 37' 19.4" 
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 89%.
 
The mask-weighted light curve exhibits multi-peaked structures, including evidence of precursor emission prior to the main burst. T90 (15-350 keV) is 229.66 +- 43.30 sec (estimated error including systematics).
 
The time-averaged spectrum from T-63.14 to T+218.21 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.63 +- 0.19.  The fluence in the 15-150 keV band is 1.7 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+1.56 sec in the 15-150 keV band
is 0.6 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1280056