[vsnet-grb-info 11848] SGR1806-20, Swift-BAT refined analysis (Trigger 519868)

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13239
SUBJECT: SGR1806-20, Swift-BAT refined analysis (Trigger 519868)
DATE:    12/04/11 12:36:01 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of the outburst from SGR1806-20 (trigger #519868)
(Barthelmy, et al., GCN Circ. 13237).  The BAT ground-calculated position is
RA, Dec = 272.163, -20.405 deg, which is 
   RA(J2000)  =  18h 08m 39.1s 
   Dec(J2000) = -20d 24' 19.0" 
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 16%.
 
The mask-weighted light curve shows a single spike starting at ~T-0.002 sec,
peaking at ~T+0.003 sec, and ending at ~T+0.15 sec with a tail out to ~T+0.4 sec.
T90 (15-350 keV) is 0.77 +- 0.32 sec (estimated error including systematics).
 
The time-averaged spectrum from T-0.06 to T+0.96 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.77 +- 0.15.  The fluence in the 15-150 keV band is 5.1 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.08 sec in the 15-150 keV band
is 10.7 +- 0.9 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/519868/BA/