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GCN Circular 30689

Subject

GRB 210822A: Swift-BAT refined analysis

Date

2021-08-23T01:10:30Z (3 years ago)

From

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

A. Y. Lien (U Tampa), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
C. B. Markwardt (GSFC), K. L. Page (U Leicester),
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-240 to T+962 sec from the recent telemetry
downlink,
we report further analysis of BAT GRB 210822A (trigger #1069788)
(Page et al., GCN Circ. 30677Loading...
 
 ).  The BAT ground-calculated position is
RA, Dec = 304.461, 5.265 deg which is
   RA(J2000)  =  20h 17m 50.7s
   Dec(J2000) = +05d 15' 54.9"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 64%.

The mask-weighted light curve shows a multi-peaked structure that
starts and peaks at T0. The main pulse structure ends at ~T+20 s,
followed by a long tail lasting till ~T+400 s. T90 (15-350 keV)
is 180.8 +- 42.7 sec (estimated error including systematics).

The time-averaged spectrum from T-0.37 to T+402.66 sec is best fit
by a simple power-law model.  The power law index of the time-averaged
spectrum is 1.30 +- 0.04.  The fluence in the 15-150 keV band
is 2.0 +- 0.04 x 10^-5 erg/cm2. The 1-sec peak photon flux measured
from T+0.00 sec in the 15-150 keV band is 27.7 +- 0.7 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/1069788/BA/