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GCN Circular 12082

Subject
SGR 1E 1841-045: Swift-BAT refined analysis
Date
2011-06-23T18:12:20Z (13 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), A. Rowlinson (U Leicester), T. Sakamoto (GSFC/UMBC),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+302 sec from the recent telemetry downlink,
we report further analysis of event from SGR 1E 1841-045 (trigger #455904)
(Rowlinson, et al., GCN Circ. 12079).  The BAT ground-calculated position is
RA, Dec = 280.329, -4.934 deg, which is 
   RA(J2000)  =  18h 41m 19.0s 
   Dec(J2000) = -04d 56' 00.9" 
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 18%.
 
The mask-weighted light curve shows a single spike that starts at ~T_zero
and ends at ~T+0.04 sec.  T90 (15-350 keV) is 0.020 +- 0.009 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-0.0 to T+0.1 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.04 +- 0.91, 
and Epeak of 32.8 +- 4.7 keV (chi squared 43.0 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 1.6 +- 0.2 x 10^-7 erg/cm2
and the 1-sec peak flux measured from T-0.43 sec in the 15-150 keV band is
3.6 +- 0.5 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 2.68 +- 0.15 (chi squared 85.2 for 57 d.o.f.).  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/455904/BA/
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