[vsnet-grb-info 10242] Swift-BAT refined analysis of outburst from 1E 1841-04.5

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11690
SUBJECT: Swift-BAT refined analysis of outburst from 1E 1841-04.5
DATE:    11/02/10 14:27:24 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),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC)
(i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+221 sec from recent telemetry downlinks,
we report further analysis of the outburst from 1E 1841-04.5 (trigger #445033)
(Barthelmy, et al., GCN Circ. 11673).  The BAT ground-calculated position is
RA, Dec = 280.332, -4.939 deg, which is 
   RA(J2000)  =  18h 41m 19.7s 
   Dec(J2000) = -04d 56' 19.9" 
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 97%.
 
The mask-weighted light curve shows two pairs of overlapping peaks
starting at ~T-0.02 and ending at ~T+0.15 sec.
T90 (15-350 keV) is 0.1 +- 0.0 sec (estimated error including systematics).
 
The time-averaged spectrum from T-0.008 to T+0.144 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index -0.26 +- 0.66, 
and Epeak of 42.2 +- 3.2 keV (chi squared 54.4 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 7.5 +- 0.6 x 10^-8 erg/cm2
and the 1-sec peak flux measured from T-0.43 sec in the 15-150 keV band is
1.3 +- 0.1 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/445033/BA/