TITLE: GCN CIRCULAR NUMBER: 13910 SUBJECT: GRB 121027A: Swift-BAT refined analysis DATE: 12/10/27 14:44:48 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), P. A. Evans (U Leicester), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-61 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 121027A (trigger #536831) (Evans, et al., GCN Circ. 13906 (not 13907)). The BAT ground-calculated position is RA, Dec = 63.598, -58.839 deg, which is RA(J2000) = 04h 14m 23.5s Dec(J2000) = -58d 50' 21.3" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 80%. The mask-weighted light curve shows a FRED with two small peaks on the tail, starting at ~T-9 sec, peaking at ~T+3 sec, with a long tail out to ~T+105 sec (or possibly to ~T+165 sec). T90 (15-350 keV) is 62.6 +- 4.8 sec (estimated error including systematics). The time-averaged spectrum from T-9.34 to T+65.33 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.82 +- 0.09. The fluence in the 15-150 keV band is 2.0 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+2.00 sec in the 15-150 keV band is 1.3 +- 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/536831/BA/