TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3918 SUBJECT: GRB 050904: BAT refined analysis of partial data set DATE: 05/09/05 02:46:12 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift D. Palmer (LANL), L. Barbier (GSFC), S. Barthelmy (GSFC), J. Cannizzo (GSFC-UMBC), J. Cummings (GSFC/NRC), D. Hullinger (GSFC/UMD), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), M. Tashiro (Saitama U.), J. Tueller (GSFC) on behalf of the Swift-BAT team: Using only a small amount of the full data set from recent telemetry downlinks, we report further analysis of Swift-BAT Trigger #153514 (Cummings, et al., GCN 3910). Due to a large backlog in data downlinking, we have only the data from T-40 to T+120 sec. We do not expect the full data set for at least another 2 days, so we are issuing this partial report. The ground-analysis position is RA,Dec 13.722,14.081 {0h54m53s, 14d04'52"} (J2000) with an uncertainty of 2.6 arcmin (radius, 90%, stat+sys). This is 3.9 arcmin from the onboard position and 0.54 arcmin from the IR afterglow position reported by Haislip et al. in GCN Circ. 3913. This is a long burst with T90 greater than 120 sec. The burst started at T+0 sec with continued emission past T+120 sec (where the downlinked data stops).