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GCN Circular 8044

Subject
GRB 080727C, Swift-BAT refined analysis
Date
2008-07-28T20:46:16Z (16 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
E. Fenimore (LANL), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC),
J. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), D. Palmer (LANL),
A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+843 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 080727C (trigger #318170)
(Parsons, et al., GCN Circ. 8035).  The BAT ground-calculated position is
RA, Dec = 32.638, 64.130 deg which is 
   RA(J2000)  =  02h 10m 33.2s 
   Dec(J2000) = +64d 07' 48.6" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 77%.
 
The mask-weighted light curve shows several overlapping peaks starting
at ~T-5 sec and ending at ~T+200 sec.  T90 (15-350 keV) is 79.7 +- 8.8 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-3.3 to T+116.3 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.87 +- 0.20, 
and Epeak of 143.2 +- 50.0 keV (chi squared 66 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 5.2 +- 0.2 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+15.23 sec in the 15-150 keV band is
2.3 +- 0.2 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.30 +- 0.05 (chi squared 81 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/318170/BA/
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