TITLE:   GCN CIRCULAR
NUMBER:  11312
SUBJECT: GRB 100928A, Swift-BAT refined analysis
DATE:    10/09/28 12:40:44 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.a.krimm@nasa.gov>

H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), V. D'Elia (ASDC), E. E. Fenimore (LANL),
N. Gehrels (GSFC), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (GSFC/UMBC),G. Sato (ISAS), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 100928A (trigger #435160)
(D'Elia, et al., GCN Circ. 11310).  The BAT ground-calculated position is
RA, Dec = 223.037, -28.542 deg which is
    RA(J2000)  =  14h 52m 09.0s
    Dec(J2000) = -28d 32' 32.5"
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 15%.

The mask-weighted light curve showed a single peak starting at T-1 with a total
duration of ~6 seconds. T90 (15-350 keV) is 3.3 +- 0.6 sec (estimated error 
including systematics).

The time-averaged spectrum from T+0.9 to T+4.4 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.79 +- 0.29.  The fluence in the 15-150 keV band is 3.5 +- 0.6 x 10-7 erg/cm2.
The 1-sec peak photon flux measured from T+1.31 sec in the 15-150 keV band
is 2.5 +- 0.5 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/435160/BA/