GCN Circular 34592
Subject
GRB 230826A: Swift-BAT refined analysis
Date
2023-08-29T15:27:50Z (8 months ago)
From
Tyler Parsotan at NASA GSFC <tyler.parsotan@nasa.gov>
Via
email
D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU),
M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-61 to T+1091 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 230826A (trigger #1187463)
(Eyles-Ferris, et al., GCN Circ. 34565). The BAT ground-calculated position is
RA, Dec = 83.048, 66.129 deg which is
RA(J2000) = 05h 32m 11.5s
Dec(J2000) = +66d 07' 43.9"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 87%.
The mask weighted light curve shows two main emission episodes where the first has
enhanced structure. T90 (15-350 keV) is 41.07 +- 2.36 sec (estimated error including systematics).
The time-averaged spectrum from T-4.26 to T+56.79 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 1.20 +- 0.22,
and Epeak of 122.3 +- 70.2 keV (chi squared 44.78 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 3.6 +- 0.1 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T+2.44 sec in the 15-150 keV band is
3.0 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.55 +- 0.05 (chi squared 52.29 for 57 d.o.f.). All the quoted errors
are at the 90% confidence level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1187463/BA/ <http://gcn.gsfc.nasa.gov/notices_s/1187463/BA/>