[vsnet-grb-info 4837] GRB 070621: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6571
SUBJECT: GRB 070621: Swift-BAT refined analysis
DATE:    07/06/22 13:52:28 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

E. Fenimore (LANL), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), B. Sbarufatti (INAF-IASFPA),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+962 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 070621 (trigger #282808)
(Sbarufatti, et al., GCN Circ. 6560).  The BAT ground-calculated position is
RA, Dec = 323.806, -24.809 deg  which is 
   RA(J2000)  =  21h 35m 13.5s 
   Dec(J2000) = -24d 48' 32" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 31%.
 
The mask-weighted light curve shows several overlapping peaks starting at ~T-20 sec
and ending at ~T+40 sec.  There is a low-significance bump (~3 sigma) from
T+70 to T+105 sec.  T90 (15-350 keV) is 33.3 +- 1.0 sec (estimated error
including systematics).
 
The time-averaged spectrum from T-5.2 to T+36.4 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.57 +- 0.06.  The fluence in the 15-150 keV band is 4.3 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+21.56 sec in the 15-150 keV band
is 2.5 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.