GCN Circular 38782

H. A. Krimm (NSF), S. D. Barthelmy (GSFC), R. Gupta (GSFC), S. Laha
(GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss
(GSFC), D. M. Palmer (LANL), K. L. Page (U Leicester), 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+800 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 250101A (trigger #1278305)
(Page et al., GCN Circ. 38752
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 ).

The BAT ground-calculated position is
RA, Dec = 37.057, 19.181 deg which is
   RA(J2000)  =  02h 28m 13.7s
   Dec(J2000) = +19d 10' 50.5"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 47%.

The mask-weighted light curve shows a weak pulse that starts at ~T0, peaks
at ~T+1 s, and ends at ~T+35 s. T90 (15-350 keV) is 34.19 +- 7.71 sec
(estimated error including systematics).

The time-averaged spectrum from T-0.22 to T+36.50 sec is best fit by a
simple power-law model.  The power law index of the time-averaged spectrum
is 2.12 +- 0.24.  The fluence in the 15-150 keV band is 6.3 +- 1.0 x 10^-07
erg/cm2. The 1-sec peak photon flux measured from T+0.95 sec in the 15-150
keV band is 0.8 +- 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/1278305/