GCN Circular 3901
A. J. Blustin (UCL-MSSL), M. Capalbi (ASDC), F. Marshall (GSFC), J. Nousek (PSU), N. Gehrels (GSFC) on behalf of the Swift UVOT team Swift/UVOT began observing the field of GRB050827 17.8 hours after the BAT trigger (Capalbi, et al., GCN 3893); previous to that, the target was unobservable due to a moon constraint. No new source with respect to the DSS image is detected in the XRT error circle (Capalbi, et al., GCN 3899) down to the following upper limits in the six filters: Filter T-range (hrs) Exp (s) 3sig_limit V 20.9-24.3 1800 20.1 B 19.5-26.2 2444 21.0 U 19.3-25.9 2699 21.1 UVW1 18.1-25.7 2939 20.6 UVM2 17.8-24.6 2531 20.7 UVW2 20.6-24.1 1800 20.8 Where T_range is the time range in hours post-trigger over which the summed images were accumulated and Exp is the total exposure time (in seconds) of the summed image. The magnitude upper limits are not corrected for extinction. These magnitudes are based on preliminary zero-points, measured in orbit, and will require refinement with further calibration.