TITLE: GCN CIRCULAR NUMBER: 12399 SUBJECT: GRB 110928A: Swift-BAT refined analysis DATE: 11/09/28 04:17:24 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), E. A. Hoversten (PSU), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 110928A (trigger #504215) (Hoversten, et al., GCN Circ. 12394). The BAT ground-calculated position is RA, Dec = 257.745, 36.547 deg, which is RA(J2000) = 17h 10m 58.7s Dec(J2000) = +36d 32' 49.3" with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 37%. The mask-weighted light curve shows a single FRED-like peak starting at ~T_zero and ending at ~T+30 sec. T90 (15-350 keV) is 26.7 +- 4.8 sec (estimated error including systematics). The time-averaged spectrum from T-0.53 to T+27.88 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.09 +- 0.30. The fluence in the 15-150 keV band is 6.9 +- 1.1 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+6.84 sec in the 15-150 keV band is 0.9 +- 0.3 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/504215/BA/