TITLE: GCN CIRCULAR NUMBER: 9494 SUBJECT: GRB 090607: Swift-BAT refined analysis of the SHB DATE: 09/06/07 11:32:02 GMT FROM: Scott Barthelmy at NASA/GSFC 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), F. E. Marshall (NASA/GSFC) D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 090607 (trigger #354299) (Marshall, et al., GCN Circ. 9491). The BAT ground-calculated position is RA, Dec = 191.194, 44.108 deg, which is RA(J2000) = 12h 44m 46.7s Dec(J2000) = +44d 06' 28.4" with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 96%. The mask-weighted light curve shows two narrow peaks. The first starts at T-0.1 sec, peaks at T+0.1 sec, and ends at T+0.7sec. The second peak starts at ~T+1.7 sec, peaks at T+2.2 sec, and ends at T+2.5 sec. There is no hint of emission out to at least T+243 sec. T90 (15-350 keV) is 2.3 +- 0.1 sec (estimated error including systematics). The time-averaged spectrum from T+0.1 to T+2.5 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.25 +- 0.30. The fluence in the 15-150 keV band is 1.1 +- 0.2 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.01 sec in the 15-150 keV band is 0.7 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level. Based on the shortness of the duration and the spectral hardness, we believe this to be a short hard burst. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/354299/BA/