TITLE: GCN CIRCULAR NUMBER: 20284 SUBJECT: GRB 161217A: Swift-BAT refined analysis DATE: 16/12/18 04:08:49 GMT FROM: Hans Krimm at NASA-GSFC/NSF A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), V. D'Elia (ASDC), N. Gehrels (GSFC), H. A. Krimm (NSF/USRA), 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-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 161217A (trigger #727167) (D'Elia, et al., GCN Circ. 20276). The BAT ground-calculated position is RA, Dec = 150.658, 52.344 deg which is RA(J2000) = 10h 02m 38.0s Dec(J2000) = +52d 20' 38.9" with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows an initial soft, weak peak from T-20 to T+20 sec, followed by a stronger peak from T+32 to T+48 sec. T90 (15-350 keV) is 1 8.2 +- 5.8 sec (estimated error including systematics). The time-averaged spectrum from T+33.77 to T+53.86 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.70 +- 0.35. The fluence in the 15-150 keV band is 1.9 +- 0.4 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+42.64 sec in the 15-150 keV band is 0.4 +- 0.1 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/727167/BA/