GCN Circular 42876

S. D. Barthelmy (GSFC), R. Caputo (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), 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 251126A (trigger #1417793)
(Caputo et al., GCN Circ. 42843
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 ).  The BAT ground-calculated position is
RA, Dec = 99.939, 54.989 deg which is
   RA(J2000)  =  06h 39m 45.4s
   Dec(J2000) = +54d 59' 21.9"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). The
partial coding was 96%.

The mask-weighted light curve shows two overlapping pulses. The first pulse
peaks at ~T+1 s, and the second pulse peaks at ~T+4 s. The overall
structure starts at ~T0 and ends at ~T+10 s. T90 (15-350 keV) is 9.00 +-
2.00 sec (estimated error including systematics).

The time-averaged spectrum from T-0.41 to T+10.59 sec is best fit by a
power law with an exponential cutoff.  This fit gives a photon index 0.43
+- 0.71,  and Epeak of 51.4 +- 8.8 keV (chi squared 58.43 for 56 d.o.f.).
For this model the total fluence in the 15-150 keV band is 4.4 +- 0.4 x
10^-07 erg/cm2 and the 1-sec peak flux measured from T+0.59 sec in the
15-150 keV band is 1.3 +- 0.2 ph/cm2/sec.  A fit to a simple power law
gives a photon index of 1.76 +- 0.12 (chi squared 72.99 for 57 d.o.f.).
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/1417793