TITLE:   GCN CIRCULAR
NUMBER:  7606
SUBJECT: GRB 080413B, Swift-BAT refined analysis
DATE:    08/04/13 17:27:57 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC), J. Cummings (GSFC/UMBC),
E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), D. Palmer (LANL),
T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC), T. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-119 to T+148 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 080413B (trigger #309111)
(Stamatikos, et al., GCN Circ. 7598).  The BAT ground-calculated position is
RA, Dec = 326.138, -19.981 deg, which is 
   RA(J2000)  =  21h 44m 33.1s 
   Dec(J2000) = -19d 58' 49.8" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 20%.
 
The mask-weighted light curve shows a single FRED-like peak starting 
at T-1.1 sec, peaking at T+0.2 sec, and returning to baseline at ~T+30 sec.
T90 (15-350 keV) is 8.0 +- 1.0 sec (estimated error including systematics).
 
The time-averaged spectrum from T-1.3 to T+10.7 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.26 +- 0.27, 
and Epeak of 73.3 +- 15.8 keV (chi squared 32.60 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 3.2 +- 0.1 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T-0.26 sec in the 15-150 keV band is
18.7 +- 0.8 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.80 +- 0.06 (chi squared 45.07 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/309111/BA/