TITLE: GCN CIRCULAR NUMBER: 15105 SUBJECT: GRB 130816A, Swift-BAT refined analysis DATE: 13/08/17 00:56:28 GMT FROM: Tilan Ukwatta at MSU T. Sakamoto (AGU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), S. T. Holland (STScI), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), D. M. Palmer (LANL), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (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 130816A (trigger #566545) (Holland , et al., GCN Circ. 15097). The BAT ground-calculated position is RA, Dec = 197.093, -58.996 deg which is RA(J2000) = 13h 08m 22.3s Dec(J2000) = -58d 59' 46.8" with an uncertainty of 2.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 35%. BAT mask-weighted light curve shows a two-peak structure. The first peak starts around T-28 sec and lasts for about 5 sec. The second peak starts around T-3 sec and ends around T+3 sec. BAT triggered on the second peak and the first peak may be considered as a precursor to the burst. T90 (15-350 keV) is 29.97 +- 1.36 sec (estimated error including systematics). The time-averaged spectrum from T-28.06 to T+2.56 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.86 +- 0.34. The fluence in the 15-150 keV band is 4.3 +- 1.0 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T-0.04 sec in the 15-150 keV band is 1.5 +- 0.2 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/566545/BA/