[vsnet-grb-info 9241] Swift-BAT refined analysis of trigger 421262

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  10724
SUBJECT: Swift-BAT refined analysis of trigger 421262
DATE:    10/05/06 20:59:14 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
A. P. Beardmore (U Leicester), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+495 sec from the recent telemetry downlink,
we report further analysis of BAT trigger #421262
(Beardmore, et al., GCN Circ. 10722).  The BAT ground-calculated position is
RA, Dec = 280.341, -4.912 deg, which is 
   RA(J2000)  =  18h 41m 21.9s 
   Dec(J2000) = -04d 54' 43.7" 
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 69%.
 
The mask-weighted light curve shows a single spike starting at ~T-0.008 sec
and ending at ~T+0.020 sec.  T90 (15-350 keV) is 0.024 +- 0.008 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-0.008 to T+0.020 sec is best fit by a
simple power-law model.  The power law index of the time-averaged spectrum is
1.87 +- 0.4.  The fluence in the 15-150 keV band is 5.0 +- 1.0 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.49 sec in the 15-150 keV band
is 0.21 +- 0.04 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/421262/BA/

We reiterate our statement in the first circular that this trigger
may be an SGR event from the known AXP source.