TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3353 SUBJECT: Swift UVOT observation of GRB 050504 DATE: 05/05/04 18:50:47 GMT FROM: Massimiliano de Pasquale at MSSL-UCL M. De Pasquale (MSSL), A. Blustin (MSSL), A. Morgan (PSU), T. Poole (MSSL), M. Still (GSFC), N. Gehrels (GSFC), K. Mason (MSSL), J. Nousek (PSU), on behalf of the Swift UVOT team The Swift UVOT began observing the field of GRB 050504 (Mereghetti et al, GCN 3348) 5.45 hours after the trigger. We have co-added all UVOT V-band exposures of GRB 050504 taken between 13:27 UT and 13:45 UT, for a total exposure time of 989 seconds. No new source is detected within a 2 arcmin radius error circle around the position given by Mereghetti et al. We obtain a three sigma upper limit from the summed image of V=20.2. The magnitudes are based on preliminary zero-points, measured in orbit, and will require refinement with further calibration.