GCN Circular 32069
Subject
GRB 220518A: Swift-BAT refined analysis
Event
Date
2022-05-19T22:19:52Z (3 years ago)
From
Tyler Parsotan at UMBC/GSFC/CRESST II <parsotat@umbc.edu>
S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), A. Y. Lien (U Tampa),
C. B. Markwardt (GSFC), 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-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 220518A (trigger #1107050)
(Gropp et al., GCN 32060). The BAT ground-calculated position is
RA, Dec = 55.340, -47.593 deg which is
RA(J2000) = 03h 41m 21.6s
Dec(J2000) = -47d 35' 36.3"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 51%.
The light curve has a peak at the trigger time and potential precursor
emission occuring slightly before the BAT trigger time.
T90 (15-350 keV) is 12.29 +- 3.07 sec (estimated error including systematics).
The time-averaged spectrum from T-8.36 to T+7.58 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.71 +- 0.21. The fluence in the 15-150 keV band is 5.7 +- 0.8 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+0.07 sec in the 15-150 keV band
is 1.8 +- 0.3 ph/cm2/sec. 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/1107050/BA/