TITLE: GCN CIRCULAR NUMBER: 19596 SUBJECT: Swift-BAT refined analysis on the bright event from SGR 1935+2154 DATE: 16/06/27 01:23:34 GMT FROM: Scott Barthelmy at NASA/GSFC J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), 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-119 to T+76 sec from the recent telemetry downlinks, we report further analysis of the bright event from SGR 1935+2154 (trigger #701590) (Barthelmy, et al., GCN Circ. 19590). The BAT ground-calculated position is RA, Dec = 293.730, 21.887 deg, which is RA(J2000) = 19h 34m 55.3s Dec(J2000) = +21d 53' 14.6" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 82%. The mask-weighted light curve shows a very rectangular profile starting at ~T-0.15 sec and ending at ~T+0.7 sec. T90 (15-350 keV) is 0.680 +- 0.004 sec (estimated error including systematics). The time-averaged spectrum from T-0.22 to T+0.67 sec best fit by a double blackbody with a lower temperature of 7.60 +- 0.42 keV and the higher temperature of 14.25 +- 0.89 keV (chi squared 40.9 for 55 d.o.f.). For reference, the simple power-law model yields a power law index of 3.09 +- 0.02 (chi squared 2025 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/701590/BA/