TITLE: GCN CIRCULAR NUMBER: 11802 SUBJECT: GRB 110318A: Swift-BAT refined analysis DATE: 11/03/18 18:14:45 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), B. Sbarufatti (INAF-OAB/IASFPA), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-114 to T+595 sec from the recent telemetry downlink, we report further analysis of BAT GRB 110318A (trigger #449542) (Sbarufatti, et al., GCN Circ. 11798). The BAT ground-calculated position is RA, Dec = 338.292, -15.278 deg, which is RA(J2000) = 22h 33m 10.0s Dec(J2000) = -15d 16' 40.9" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 27%. The mask-weighted light curve shows a small precursor peak between T-8 and T-2 sec. The main peak starts at ~T-1 sec, peaks at ~T+1 sec, and ends at ~T+15 sec. T90 (15-350 keV) is 16.0 +- 1.7 sec (estimated error including systematics). The time-averaged spectrum from T-13.0 to T+10.6 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.05 +- 0.23, and Epeak of 94.3 +- 23.7 keV (chi squared 43.1 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 4.9 +- 0.2 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+1.95 sec in the 15-150 keV band is 8.0 +- 0.5 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.58 +- 0.05 (chi squared 59.4 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/449542/BA/