TITLE: GCN CIRCULAR NUMBER: 17046 SUBJECT: GRB 141109B: Swift-BAT refined analysis DATE: 14/11/09 18:11:35 GMT FROM: Scott Barthelmy at NASA/GSFC J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), A. Melandri (INAF-OAB), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from recent telemetry downlinks, we report further analysis of BAT GRB 141109B (trigger #618032) (Melandri, et al., GCN Circ. 17038). The BAT ground-calculated position is RA, Dec = 222.453, 73.141 deg, which is RA(J2000) = 14h 49m 48.8s Dec(J2000) = +73d 08' 26.3" with an uncertainty of 2.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 75%. The mask-weighted light curve shows a couple overlapping peaks starting at ~T-20 sec, peaking at ~T+28 sec, and ending at ~T+60 sec. T90 (15-350 keV) is 54.2 +- 5.0 sec (estimated error including systematics). The time-averaged spectrum from T-13.18 to T+44.18 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.85 +- 0.22. The fluence in the 15-150 keV band is 6.3 +- 0.9 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+28.05 sec in the 15-150 keV band is 0.4 +- 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/618032/BA/