GRB 170531***A***, Swift-BAT refined analysis
 
<somebody goes first>
<add the BA alphabetically>
S. D. Barthelmy (GSFC), 
J. R. Cummings (CPI),
H. A. Krimm (NSF/USRA),
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-687 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170531***A*** (trigger #755354)
(NAME, et al., GCN Circ. xxxx).  The BAT ground-calculated position is
RA, Dec = 286.899, -16.409 deg which is 
   RA(J2000)  =  19h 07m 35.8s 
   Dec(J2000) = -16d 24' 33.3" 
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 96%.
 
[Description about the mask-weighted light curve]
T90 (15-350 keV) is 170.3 +- 9.1 sec (estimated error including systematics).
 
The time-averaged spectrum from T+0.2 to T+181.6 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.94 +- 0.15.  The fluence in the 15-150 keV band is 1.9 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+42.71 sec in the 15-150 keV band
is 0.7 +- 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/755354/BA/