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GCN Circular 10724

Subject
Swift-BAT refined analysis of trigger 421262
Date
2010-05-06T20:59:14Z (14 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@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 1.4 +- 0.3 x 10^-8 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.

[GCN OPS NOTE(07may10): Per author's request, the fluence value
was corrected to from 5e-7 to 1.4e-8. We apologize for the inconvenience.]
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