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GCN Circular 30489

Subject

GRB 210722A: Swift-BAT refined analysis

Date

2021-07-23T20:37:20Z (3 years ago)

From

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

S. D. Barthelmy (GSFC), P. D'Avanzo (INAF-OAB)
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(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 210722A (trigger #1061223)
(D'Avanzo et al., GCN Circ. 30475Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 27.031, -6.347 deg which is
   RA(J2000)  =  01h 48m 07.4s
   Dec(J2000) = -06d 20' 49.9"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 43%.

The mask-weighted light curve shows a single-peaked structure that
starts at ~T-5 s, peaks at ~T0, and ends at ~T+30 s, with
some weak tail emission that lasts until ~T+60 s. T90 (15-350 keV)
is 50.20 +- 10.54 sec (estimated error including systematics).

The time-averaged spectrum from T-4.40 to T+59.59 sec is best fit by
a simple power-law model.  The power law index of the time-averaged
spectrum is 1.62 +- 0.14.  The fluence in the 15-150 keV band
is 2.5 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured
from T+1.00 sec in the 15-150 keV band is 2.2 +- 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/1061223/BA/