TITLE: GCN CIRCULAR NUMBER: 8800 SUBJECT: GRB 090111, Swift-BAT refined analysis DATE: 09/01/12 20:52:55 GMT FROM: Hans Krimm at NASA-GSFC M. Stamatikos (GSFC/ORAU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 090111 (trigger #339696) (Sakamoto et al., GCN Circ. 8795). The BAT ground-calculated position is RA, Dec = 251.656, 0.067 deg which is RA(J2000) = 16h 46m 37.4s Dec(J2000) = +00d 04' 01.5" with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 82%. The mask-weighted light curve shows two peaks of roughly equal intensity. The first lasts from T-3 sec to T+9 sec and the second from T+10 to T+26 seconds. T90 (15-350 keV) is 24.8 +- 2.7 sec (estimated error including systematics). The time-averaged spectrum from T-2.9 to T+25.6 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.37 +- 0.17. The fluence in the 15-150 keV band is 6.2 +- 0.6 x 10-7 erg/cm2. The 1-sec peak photon flux measured from T+10.70 sec in the 15-150 keV band is 0.9 +- 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/339696/BA/