TITLE: GCN CIRCULAR NUMBER: 39617 SUBJECT: GRB 250306A: Swift-BAT refined analysis DATE: 25/03/07 18:38:30 GMT FROM: Rahul Gupta at NASA GSFC rahul.gupta@nasa.gov
T. Parsotan (GSFC), S. D. Barthelmy (GSFC),
P. A. Evans (U Leicester), 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+961 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 250306A (trigger #1293340)
(Evans et al., GCN Circ. 39606). The BAT ground-calculated position is
RA, Dec = 354.724, -47.998 deg which is
RA(J2000) = 23h 38m 53.7s
Dec(J2000) = -47d 59' 52.8"
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 13%.
The mask-weighted BAT light curve shows a distinct peak at around BAT trigger time,
followed by a rapid decay and a quieter post-peak phase.
T90 (15-350 keV) is 11.44 +- 2.44 sec (estimated error including systematics).
The time-averaged spectrum from T-1.52 to T+19.04 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 0.87 +- 0.24,
and Epeak of 132.8 +- 45.6 keV (chi squared 62.11 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 8.9 +- 0.3 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T+0.18 sec in the 15-150 keV band is
35.9 +- 1.6 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.37 +- 0.05 (chi squared 75.58 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/1293340
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