TITLE: GCN CIRCULAR NUMBER: 23533 SUBJECT: GRB 181213A: Swift-BAT refined analysis DATE: 18/12/14 05:04:44 GMT FROM: Amy Lien at GSFC J. R. Cummings (CPI), S. D. Barthelmy (GSFC), P. A. Evans (U Leicester), H. A. Krimm (NSF/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-240 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 181213A (trigger #876016) (Evans et al., GCN Circ. 23525). The BAT ground-calculated position is RA, Dec = 248.210, 78.500 deg which is RA(J2000) = 16h 32m 50.5s Dec(J2000) = +78d 30' 00.7" with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 21%. The mask-weighted light curve shows a multi-peaked structure that starts at ~T-1 s and ends at ~T+16 s. Note that the burst went out of the BAT field of view at ~T+100 s. T90 (15-350 keV) is 15.31 +- 1.24 sec (estimated error including systematics). The time-averaged spectrum from T-0.70 to T+15.94 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.57 +- 0.20. The fluence in the 15-150 keV band is 1.5 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+1.16 sec in the 15-150 keV band is 2.1 +- 0.6 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/876016/BA/