GCN Circular 38387

T. Parsotan (GSFC), S. D. Barthelmy (GSFC), R. Brivio (INAF-OAB), 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-240 to T+899 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 241128A (trigger #1270999)
(Brivio et al., GCN Circ. 38367
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 ).  The BAT ground-calculated position is
RA, Dec = 273.724, 33.492 deg which is
   RA(J2000)  =  18h 14m 53.7s
   Dec(J2000) = +33d 29' 32.9"
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The
partial coding was 52%.

The mask-weighted light curve shows a multi-pulse structure that starts at
~T0 and ends at ~T+240 s. The main pulse starts at ~T0, peaks at ~T+3 s,
and ends at ~T+10 s. In addition, there is a weak pulse at ~T+220 s. T90
(15-350 keV) is 238.32 +- 15.83 sec (estimated error including systematics).

The time-averaged spectrum from T-0.86 to T+244.08 sec is best fit by a
simple power-law model.  The power law index of the time-averaged spectrum
is 1.54 +- 0.31.  The fluence in the 15-150 keV band is 1.1 +- 0.2 x 10^-06
erg/cm2. The 1-sec peak photon flux measured from T+2.88 sec in the 15-150
keV band is 1.0 +- 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/1270999