TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4476 SUBJECT: GRB 060109: Swift-BAT refined analysis DATE: 06/01/11 00:21:10 GMT FROM: Takanori Sakamoto at NASA/GSFC D. Palmer (LANL), M. Ajello (MPE), L. Barbier (GSFC), S. Barthelmy (GSFC), J. Cummings (GSFC/ORAU), E. Fenimore (LANL), R. Fink (GSFC), N. Gehrels (GSFC), D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (ISAS), J. Tueller (GSFC), on behalf of the Swift-BAT team: Using the data set from T-299.2 to T+302.9 sec from the recent telemetry downlink, we report further analysis of BAT GRB 060109 (trigger #176620) (De Pasquale, et al., GCN 4455). The BAT ground-calculated position is (RA,Dec) = 282.739, 32.009 {18h 50m 57.3s, 32d 0' 32.6"} (deg; J2000) +- 3.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 92%. The mask-tagged lightcurve shows a double peak structure. The first peak has a duration of ~20 sec. starting from T-2 sec. And the second peak has a duration of ~40 sec. starting from T+75 sec. T90 (15-350 keV) is (116 +- 3) sec (estimated error including systematics). Over the full burst interval (T-0.4 to T+126.8 sec), the power law index of the time-averaged spectrum is 1.96 +- 0.25. The fluence in the 15-150 keV band is (6.4 +- 1.0) x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+90.19 sec in the 15-150 keV band is (0.5 +- 0.1) ph/cm2/sec. All the quoted errors are at the 90% confidence level.