GCN Circular 31981
Subject
GRB 220430A: Swift-BAT refined analysis
Date
2022-05-01T15:16:28Z (2 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
S. D. Barthelmy (GSFC), E. Ambrosi (INAF-IASFPA),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
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-204 to T+843 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 220430A (trigger #1104692)
(Ambrosi et al., GCN Circ. 31972). The BAT ground-calculated position is
RA, Dec = 97.616, 9.547 deg which is
RA(J2000) = 06h 30m 27.9s
Dec(J2000) = +09d 32' 50.1"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
The mask-weighted light curve shows two major pulse emissions. The first
one starts at ~T-7 s, peaks at ~T+20 s, and ends at ~T+30 s. It is
followed by another larger pulse with several peaks. The largest peak
occurs at ~T+42 s. The burst emission ends at ~T+100 s. T90 (15-350 keV)
is 43.10 +- 0.57 sec (estimated error including systematics).
The time-averaged spectrum from T-6.53 to T+94.36 sec is best fit by
a simple power-law model. The power law index of the time-averaged
spectrum is 1.24 +- 0.02. The fluence in the 15-150 keV band is
4.4 +- 0.05 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from
T+42.00 sec in the 15-150 keV band is 29.6 +- 0.6 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/1104692/BA/