TITLE:   GCN CIRCULAR
NUMBER:  30043
SUBJECT: GRB 210517A: Swift-BAT refined analysis
DATE:    21/05/17 20:06:05 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC),  V. D'Elia (SSDC & INAF-OAR), 
H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-240 to T+659 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 210517A (trigger #1048783)
(D'Elia, et al., GCN Circ. 30032).  The BAT ground-calculated position is
RA, Dec = 358.190, -39.104 deg which is 
   RA(J2000)  =  23h 52m 45.5s 
   Dec(J2000) = -39d 06' 15.0" 
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 78%.

The mask-weighted light curve shows a single peak of three-second duration
near the trigger time.  T90 (15-350 keV) is 3.06 +- 1.4 sec (estimated error including 
systematics).

The time-averaged spectrum from T-0.17 to T+3.13 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.85 +- 0.25.  The fluence in the 15-150 keV band is 1.5 +- 0.3 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.18 sec in the 15-150 keV band
is 1.5 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The position of this burst on the BAT T90-Hardness diagram suggests that it is a 
long GRB.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1048783/BA/