TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4235 SUBJECT: GRB 051109A: Swift-UVOT Observations DATE: 05/11/09 19:55:43 GMT FROM: Stephen Holland at USRA/NASA/GSFC/SSC GRB 051109A: Swift-UVOT Observations S. T. Holland (GSFC/USRA), S. Campana (INAF-OAB), P. Smith (UCL/MSSL), H. Huckle (UCL/MSSL), & N. Gehrels (GSFC) on behalf of the Swift-UVOT team report: The Swift-UVOT began observing the field of GRB 051109A (BAT Trigger 163136; Palmer, et al. GCN Circular 4213) at 2005-11-09T01:14:09, 109 seconds after the burst. We detect an optical transient at RA(J2000) = 22:01:15.32 Dec(J2000) = +40:49:23.7 with a positional uncertainty of +/-0.5 arcsec (90% confidence), in agreement with the position of Rykoff, et al. (2005, GCN Circular 4211). The transient has V = 16.49 +/- 0.07 (1-sigma, statistical) in an 89 s exposure starting at 2005-11-09T01:14:23, 123 seconds after the BAT trigger. This value supercedes the approximate magnitude given in Palmer, et al. (2005, GCN Circular 4213). This magnitude has not been corrected for Galactic extinction. Further observations and analysis are underway.