TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4779 SUBJECT: Further UVOT Observations of the Candidate Optical Afterglow for GRB 060218 DATE: 06/02/18 17:01:28 GMT FROM: Frank Marshall at GSFC F. Marshall (GSFC), S. Immler (GSFC/USRA) and G. Cusumano (IASF-Pa INAF) report on behalf of the Swift team: The UVOT source reported by Cusumano et al. (GCN 4775) is detected in all four UVOT finding chart exposures ranging from 153s to 1036s from the burst trigger as shown in the table below. There is marginal evidence for brightening in the V filter. The revised source position is 03:21:39.71 +16:52:02.6 (J2000) with an estimated 1-sigma error of about 1.0". This position is within the XRT error circle (Kennea et al. GCN 4776). We note the existence of a source in the USNO-B1 catalog at 03:21:39.69 +16:52:02.2 with a B2 magnitude of 20.67 and an R2 magnitude of 20.3. Further UVOT observations are underway to search for fading of this afterglow candidate. T_start Exposure Filter Mag Mag. Range (1-sigma) 153 200 V 19.6 19.1 - 20.3 359 155 B 19.4 19.2 - 19.6 830 127 B 19.3 19.1 - 19.5 1036 148 V 18.4 18.2 - 18.6