TITLE: GCN CIRCULAR NUMBER: 31149 SUBJECT: GRB 211129A: Swift-BAT refined analysis DATE: 21/11/30 03:22:44 GMT FROM: Amy Lien at GSFC D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. D. Gropp (PSU), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+800 sec from the recent telemetry downlink, we report further analysis of BAT GRB 211129A (trigger #1085430) (Gropp et al., GCN Circ. 31136). The BAT ground-calculated position is RA, Dec = 274.565, 31.781 deg which is RA(J2000) = 18h 18m 15.6s Dec(J2000) = +31d 46' 51.5" with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 83%. The mask-weighted light curve shows a multi-peaked structure that starts at ~T-2 s and ends at ~T+120 s. The three main peaks occur at ~T+1 s, ~T+29 s, and ~T+91 s, respectively. T90 (15-350 keV) is 113.01 +- 9.14 sec (estimated error including systematics). The time-averaged spectrum from T-1.80 to T+124.11 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.75 +- 0.13. The fluence in the 15-150 keV band is 2.3 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.99 sec in the 15-150 keV band is 1.5 +- 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/1085430/BA/