TITLE:   GCN CIRCULAR
NUMBER:  32090
SUBJECT: GRB 220521A: Swift-BAT refined analysis
DATE:    22/05/22 16:41:20 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

A. Y. Lien (U Tampa), S. D. Barthelmy (GSFC),
S. Dichiara (PSU), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), 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-240 to T+962 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 220521A (trigger #1107466)
(Dichiara et al., GCN Circ. 32076).  The BAT ground-calculated position is
RA, Dec = 275.218, 10.372 deg which is
   RA(J2000)  =  18h 20m 52.3s
   Dec(J2000) = +10d 22' 20.0"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 46%.

The mask-weighted light curve shows a multi-peaked structure that
starts at ~T0 and ends at ~T+16 s. The two main peaks occur at ~T+0.5 s
and ~T+10 s, respectively. T90 (15-350 keV) is 13.55 +- 2.69 sec (estimated
error including systematics).

The time-averaged spectrum from T-0.23 to T+16.17 sec is best fit by
a simple power-law model.  The power law index of the time-averaged
spectrum is 1.97 +- 0.18.  The fluence in the 15-150 keV band
is 8.1 +- 0.8 x 10^-7 erg/cm2. The 1-sec peak photon flux measured
from T-0.18 sec in the 15-150 keV band is 4.7 +- 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/1107466/BA/