GRB 210731***A***: Swift-BAT refined analysis
 
<somebody goes first>
<add the BA alphabetically>
S. D. Barthelmy (GSFC), 
J. R. Cummings (CPI),
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 210731***A*** (trigger #1062273)
(NAME, et al., GCN Circ. xxxx).  The BAT ground-calculated position is
RA, Dec = 256.009, -37.867 deg which is 
   RA(J2000)  =  17h 04m 02.2s 
   Dec(J2000) = -37d 52' 01.9" 
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 89%.
 
[Description about the mask-weighted light curve]
T90 (15-350 keV) is 790.98 +- 33.90 sec (estimated error including systematics).
 
The time-averaged spectrum from TTBD to TTBD sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.64 +- 0.88, 
and Epeak of 8.6 +- 0.0 keV (chi squared 65.89 for 52 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 8.9 +- 1.0 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T-56.31 sec in the 15-150 keV band is
0.7 +- 0.5 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 3.23 +- 0.16 (chi squared 72.09 for 53 d.o.f.).  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/1062273/BA/