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GCN Circular 31485

Subject
GRB 220117A: Swift-BAT refined analysis
Date
2022-01-18T15:35:31Z (2 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
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),
A. Melandri (INAF-OAB), 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+939 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 220117A (trigger #1093592)
(Melandri et al., GCN Circ. 31466).  The BAT ground-calculated position is
RA, Dec = 91.590, -28.402 deg which is
   RA(J2000)  =  06h 06m 21.5s
   Dec(J2000) = -28d 24' 08.5"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 26%.

The mask-weighted light curve shows a multi-peaked structure that
starts at ~T+15 s and ends at ~T+65 s. The two larger peaks occur
at ~T+15 s and ~T+44 s, respectively. T90 (15-350 keV) is
49.81 +- 2.37 sec (estimated error including systematics).

The time-averaged spectrum from T+14.79 to T+66.14 sec is best fit
by a simple power-law model.  The power law index of the time-averaged
spectrum is 1.84 +- 0.18.  The fluence in the 15-150 keV band
is 1.6 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured
from T+14.81 sec in the 15-150 keV band is 1.9 +- 0.4 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/1093592/BA/
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