TITLE: GCN CIRCULAR NUMBER: 8507 SUBJECT: GRB 081109A, Swift-BAT refined analysis DATE: 08/11/09 16:42:12 GMT FROM: Scott Barthelmy at NASA/GSFC C. B. Markwardt (GSFC/UMD), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), S. Immler (CRESST/GSFC/UMD), H. A. Krimm (GSFC/USRA), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (GSFC/ORAU), 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 081109A (trigger #334112) (Immler, et al., GCN Circ. 8500). The BAT ground-calculated position is RA, Dec = 330.798, -54.711 deg, which is RA(J2000) = 22h 03m 11.5s Dec(J2000) = -54d 42' 40.5" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 73%. The mask-weighted light curve shows a smooth rise to a single peak starting at ~T-90 sec, peaking at ~T+5 sec, and roughly exponentially decaying back to baseline at ~T+400 sec. T90 (15-350 keV) is 190 +- 60 sec (estimated error including systematics). The time-averaged spectrum from T-15.9 to T+416.1 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.72 +- 0.09. The fluence in the 15-150 keV band is 3.6 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+7.64 sec in the 15-150 keV band is 1.1 +- 0.0 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/334112/BA/