TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3912 SUBJECT: GRB050904: P60 Observations DATE: 05/09/04 07:58:41 GMT FROM: Derek Fox at PSU Derek B. Fox (Penn State) and S. Bradley Cenko (Caltech) report on behalf of a larger collaboration: "We have imaged the BAT and XRT localization region for GRB050904 (Swift Trigger 153514; Cummings et al., GCN 3910) in a series of exposures with the Palomar Robotic 60-inch Telescope (P60). At the following mean epochs, and to the following limits in R- and i-band, we identify no new sources within the XRT localization region in our coadded images: Time (UT) Delta Limit (mag) =================================== 05:25 +3h33m R > 20.8 05:41 +3h49m i > 19.7 =================================== Our photometric calibration is performed against the USNO-B1.0 catalog R-band and I-band magnitudes for this field for our R- and i-filter images, respectively. Our observations of this field are continuing."