TITLE: GCN CIRCULAR NUMBER: 9899 SUBJECT: GRB 090904A: Swift/UVOT Refined Analysis DATE: 09/09/05 05:46:33 GMT FROM: Tyler Pritchard at PSU T. A. Pritchard (PSU), C. A. Swenson (PSU) and M. Perri (ASDC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of GRB 090904A, 141 seconds after the BAT trigger (M. Perri et al., GCN Circ. 9879). We do not detect any source at the UVOT-enhanced XRT position (M.R. Goad, GCN Circ. 9885). The 3-sigma upper limits for the exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag (3-sigma upper limit) ------------------------------------------------------------- white 141 1189 341 > 21.57 v 629 1078 58 > 18.72 b 555 1177 58 > 19.59 u 299 1152 285 > 20.43 uvw1 679 1127 58 > 19.11 uvm2 827 847 19 > 17.61 uvw2 605 1054 58 > 19.17 ------------------------------------------------------------- The quoted upper limits have not been corrected for the expected Galactic extinction corresponding to a reddeningalong the line of sight of E_(B-V) = 0.1 mag (Schlegel et al., 1998, ApJS, 500, 525). All photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627).