TITLE: GCN CIRCULAR NUMBER: 33541 SUBJECT: GRB 230328B: Swift-BAT refined analysis DATE: 23/03/30 03:44:23 GMT FROM: Tyler Parsotan at UMBC/GSFC/CRESST II parsotat@umbc.edu
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), D. M. Palmer (LANL),
T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU),
M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 230328B (trigger #1162001)
(Gropp, et al., GCN Circ. 33527). The BAT ground-calculated position is
RA, Dec = 291.037, 80.013 deg which is
RA(J2000) = 19h 24m 08.8s
Dec(J2000) = +80d 00' 45.3"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 46%.
The mask weighted light curve has a double peaked structure.
The light curve does not show an early afterglow as was stated in the original GCN.
T90 (15-350 keV) is 19.23 +- 3.82 sec (estimated error including systematics).
The time-averaged spectrum from T-7.38 to T+25.49 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 1.22 +- 0.29,
and Epeak of 99.7 +- 59.7 keV (chi squared 29.53 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 4.3 +- 0.2 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T+0.26 sec in the 15-150 keV band is
8.4 +- 0.5 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.63 +- 0.07 (chi squared 35.85 for 57 d.o.f.). All the quoted errors
are at the 90% confidence level.
The results of the batgrbproduct analysis are available at