GRB 210820***A***, Swift-BAT refined analysis
 
<somebody goes first>
<add the BA alphabetically>
S. D. Barthelmy (GSFC), 
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),
T. Sakamoto (AGU),
M. Stamatikos (OSU)
(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 210820***A*** (trigger #1069551)
(NAME, et al., GCN Circ. xxxx).  The BAT ground-calculated position is
RA, Dec = 20.625, 4.647 deg which is 
   RA(J2000)  =  01h 22m 30.0s 
   Dec(J2000) = +04d 38' 48.5" 
with an uncertainty of 3.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 48%.
 
[Description about the mask-weighted light curve]
T90 (15-350 keV) is 151.7 +- 20.6 sec (estimated error including systematics).
 
The time-averaged spectrum from T+0.8 to T+160.2 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.10 +- 0.22.  The fluence in the 15-150 keV band is 1.3 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+10.92 sec in the 15-150 keV band
is 0.8 +- 0.2 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/1069551/BA/
 
 
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## Special note (please do not include this in the email circular):
## Becuase E0 = 13.1618 is outside of the BAT energy range (15-350 keV),
## A simple power-law model is chosen despite delta chi2 > 6.
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