TITLE: GCN CIRCULAR NUMBER: 22512 SUBJECT: GRB 180316A: Swift-BAT refined analysis DATE: 18/03/16 19:49:29 GMT FROM: Amy Lien at GSFC J. R. Cummings (CPI), S. D. Barthelmy (GSFC), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), A. Melandri (INAF-OAB), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (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 180316A (trigger #814677) (Melandri et al., GCN Circ. 22500). The BAT ground-calculated position is RA, Dec = 265.422, 0.737 deg which is RA(J2000) = 17h 41m 41.3s Dec(J2000) = +00d 44' 14.3" with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 29%. The mask-weighted light curve shows a main structure with several overlapping pulses that starts at ~ T-15 s and ends at ~ T+30 s. The major peak occurs at ~ T+1 s. In addition, there are some weak emission before the main structure that starts at ~ T-80 s, and a weak tail afterward that lasts until ~ T+40 s. T90 (15-350 keV) is 87.0 +- 20.6 sec (estimated error including systematics). The time-averaged spectrum from T-79.73 to T+37.27 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.46 +- 0.12. The fluence in the 15-150 keV band is 4.9 +- 0.4 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+1.27 sec in the 15-150 keV band is 3.3 +- 0.5 ph/cm2/sec. All the quoted errors are at the 90% confidence level.