TITLE:   GCN CIRCULAR
NUMBER:  6786
SUBJECT: GRB 070913:  Swift-BAT refined analysis
DATE:    07/09/13 15:08:58 GMT
FROM:    Hans Krimm at NASA-GSFC  <krimm@milkyway.gsfc.nasa.gov>

G. Sato (GSFC/ISAS), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL),
A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), 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+523 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 070913 (trigger #290843)
(Markwardt, et al., GCN Circ. 6782, 6785).  The BAT ground-calculated 
position is
RA, Dec = 228.737 -24.278 deg which is
    RA(J2000) = 15h 14m 57s
    Dec(J2000) = -24d 16' 42"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 51%.

The mask-weighted light curve shows a single peak of about 4 seconds duration.
T90 (15-350 keV) is 3.2 +- 0.3 sec (estimated error including systematics).

The time-averaged spectrum from T-2.4 to T+1.2 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.61 +- 0.19.  The fluence in the 15-150 keV band is 2.5 +- 0.3 x 
10^-07 erg/cm2.
The 1-sec peak photon flux measured from T-0.34 sec in the 15-150 keV band
is 1.4 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.