TITLE: GCN CIRCULAR NUMBER: 8243 SUBJECT: GRB 080916A, Swift-BAT refined analysis DATE: 08/09/16 17:06:23 GMT FROM: Scott Barthelmy at NASA/GSFC W. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), 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), A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU), H. Ziaeepour (UCL-MSSL) (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 080916A (trigger #324895) (Ziaeepour, et al., GCN Circ. 8237). The BAT ground-calculated position is RA, Dec = 336.289, -57.026 deg, which is RA(J2000) = 22h 25m 09.3s Dec(J2000) = -57d 01' 33.7" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 82%. The mask-weighted light curve shows two overlapping FRED peaks starting at ~T-3 sec and ending at ~T+100 sec. T90 (15-350 keV) is 60 +- 7 sec (estimated error including systematics). The time-averaged spectrum from T-2.4 to T+88.6 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.17 +- 0.21, and Epeak of 94.6 +- 23.0 keV (chi squared 48.0 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 4.0 +- 0.1 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+1.25 sec in the 15-150 keV band is 2.7 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.63 +- 0.05 (chi squared 64.5 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/324895/BA/