[vsnet-grb-info 28326] GRB 210708B: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30429
SUBJECT: GRB 210708B: Swift-BAT refined analysis
DATE:    21/07/09 10:39:56 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm at nsf.gov>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU), B. Sbarufatti (PSU),
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 210708B (trigger #1059494)
(Sbarufatti, et al., GCN Circ. 30417).  The BAT ground-calculated position is
RA, Dec = 142.594, 14.523 deg which is 
   RA(J2000)  =  09h 30m 22.5s 
   Dec(J2000) = +14d 31' 22.6" 
with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 74%.

The mask-weighted light curve shows a broad peak with some sub-structure.
Emission begins around T-100 sec, peaks near the trigger time and decays
to background by T+200 sec.  The burst position was not in the field of view of
the BAT until about T-150 sec.  T90 (15-350 keV) is 298.43 +- 47.32 sec 
(estimated error including systematics).

The time-averaged spectrum from -99.8 to 263.7 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.62 +- 0.26.  The fluence in the 15-150 keV band is 2.2 +- 0.4 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+2.84 sec in the 15-150 keV band
is 0.0 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 

We note that in the original GCN circular, the event was described as a possible
burst.  Analysis of the full data set shows that the event is indeed a GRB.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1059494/BA/