TITLE: GCN CIRCULAR NUMBER: 17213 SUBJECT: GRB 141221A: Swift-BAT refined analysis DATE: 14/12/21 19:28:45 GMT FROM: Scott Barthelmy at NASA/GSFC T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), E. Sonbas (NASA/GSFC/Adiyaman Univ.), M. Stamatikos (OSU), J. Tueller (GSFC) (i.e. the Swift-BAT team): Using the data set from T-61 to T+242 sec from recent telemetry downlinks, we report further analysis of BAT GRB 141221A (trigger #622006) (Sonbas, et al., GCN Circ. 17206). The BAT ground-calculated position is RA, Dec = 198.283, 8.197 deg, which is RA(J2000) = 13h 13m 07.9s Dec(J2000) = +08d 11' 49.8" with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 78%. The mask-weighted light curve shows some low-level precursor emission starting at ~T-23 sec with the first peak starting at ~T-3 sec, peaking at ~T+1 sec, and the second peak peaking at ~T+14 sec, and ending at T+35 sec. T90 (15-350 keV) is 36.9 +- 4.0 sec (estimated error including systematics). The time-averaged spectrum from T-24.11 to T+20.33 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.74 +- 0.08. The fluence in the 15-150 keV band is 2.1 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.10 sec in the 15-150 keV band is 3.1 +- 0.2 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/622006/BA/