TITLE: GCN CIRCULAR NUMBER: 15108 SUBJECT: GRB 130816B, Swift-BAT refined analysis DATE: 13/08/17 16:08:14 GMT FROM: Tilan Ukwatta at MSU M. Stamatikos (OSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 130816B (trigger #566561) (Stamatikos, et al., GCN Circ. 15099). The BAT ground-calculated position is RA, Dec = 170.049, -57.527 deg which is RA(J2000) = 11h 20m 11.8s Dec(J2000) = -57d 31' 37.7" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).The partial coding was 98%. BAT mask-weighted light curve shows a single peak starting from ~T-10 sec peaking around T+0 sec and ending at ~T+4 sec. T90 (15-350 keV) is 10.00 +- 3.61 sec (estimated error including systematics). The time-averaged spectrum from T-6.50 to T+6.50 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.45 +- 0.93, and Epeak of 47.3 +- 10.8 keV (chi squared 35.98 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 2.7 +- 0.4 x 10^-07 erg/cm2 and the 1-sec peak flux measured from T+0.50 sec in the 15-150 keV band is 0.9 +- 0.1 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.82 +- 0.17 (chi squared 44.98 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/566561/BA/