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GCN Circular 31499

Subject

GRB 220118A: Swift-BAT refined analysis

Date

2022-01-19T21:02:06Z (2 years ago)

From

Amy Lien at GSFC <amy.y.lien@nasa.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC),
N. J. Klingler (GSFC/UMBC/CRESSTII), 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), 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 220118A (trigger #1093742)
(Klingler et al., GCN Circ. 31490Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 192.277, 22.911 deg which is
   RA(J2000)  =  12h 49m 06.4s
   Dec(J2000) = +22d 54' 37.8"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 22%.

The mask-weighted light curve shows a single-peaked structure that
starts at ~T-4 s, peaks at ~T+1 s, and ends at ~T+10 s.
T90 (15-350 keV) is 10.61 +- 1.78 sec (estimated error including
systematics).

The time-averaged spectrum from T-3.90 to T+9.54 sec is best fit
by a simple power-law model.  The power law index of the time-averaged
spectrum is 1.67 +- 0.12.  The fluence in the 15-150 keV band
is 1.8 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from
T+0.68 sec in the 15-150 keV band is 3.3 +- 0.5 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/1093742/BA/