TITLE: GCN CIRCULAR NUMBER: 15635 SUBJECT: GRB 131229A: Swift-BAT refined analysis DATE: 13/12/29 19:15:46 GMT FROM: Scott Barthelmy at NASA/GSFC T. N. Ukwatta (MSU), 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 (NASA/UMBC), C. B. Markwardt (GSFC), M. J. Page (UCL-MSSL), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), J. Tueller (GSFC) (i.e. the Swift-BAT team): Using the data set from T-240 to T+443 sec from recent telemetry downlinks, we report further analysis of BAT GRB 131229A (trigger #582374) (Page, et al., GCN Circ. 15627). The BAT ground-calculated position is RA, Dec = 85.236, -4.401 deg, which is RA(J2000) = 05h 40m 56.6s Dec(J2000) = -04d 24' 04.4" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 97%. The mask-weighted light curve shows many overlapping peaks starting at ~T-1 sec, peaking at ~T+14 sec, and ending at ~T+17 sec with a long low-level tail exteding out to ~T+430 sec, at which point the BAT data stops due to entering the SAA. T90 (15-350 keV) is 13.86 +- 0.43 sec (estimated error including systematics). The time-averaged spectrum from T+0.08 to T+27.04 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.02 +- 0.03. The fluence in the 15-150 keV band is 6.6 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+13.55 sec in the 15-150 keV band is 10.7 +- 0.3 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/582374/BA/