TITLE: GCN CIRCULAR NUMBER: 14096 SUBJECT: GRB 121217A: Swift-BAT refined analysis DATE: 12/12/19 22:23:48 GMT FROM: Scott Barthelmy at NASA/GSFC J. R. Cummings (GSFC/UMBC), T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), A. M. Parsons (GSFC), G. Sato (ISAS), M. H. Siegel (PSU), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from recent telemetry downlinks, we report further analysis of BAT GRB 121217A (trigger #542441) (Siegel, et al., GCN Circ. 14089). The BAT ground-calculated position is RA, Dec = 153.708, -62.354 deg, which is RA(J2000) = 10h 14m 50.0s Dec(J2000) = -62d 21' 15.5" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 99%. The mask-weighted light curve shows two well-separated periods of emission. The first starts at ~T-110 sec with weak emission, then peaks at ~T+1 sec, and returns to baseline at ~T+80 sec. The second period of emission starts at ~T+500 sec, with weak peaks at ~T+500 and ~T+610 sec and the main peak at ~T+730 sec and returns to baseline out past T+960 sec (where the data ends). There are enough differences in the profiles of these two periods of emission to conclude they are not gravitationally lensed. T90 (15-350 keV) is 778 +- 16 sec (estimated error including systematics). The time-averaged spectrum from T-17.7 to T+783.8 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.53 +- 0.08. The fluence in the 15-150 keV band is 6.2 +- 0.3 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+735.96 sec in the 15-150 keV band is 1.8 +- 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/542441/BA/