TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5625 SUBJECT: GRB 060926: Swift-UVOT Detections DATE: 06/09/27 02:20:21 GMT FROM: Pete Roming at PSU P. Roming (PSU) and S. T. Holland (GSFC/USRA) report on behalf of the Swift-UVOT team: The Swift UVOT began observing GRB 060926, 57 seconds after the BAT trigger (GCN 5612). We detect a source at the 4.8- and 4.3-sigma levels in the V- and UVW1- (251 nm) filters, respectively. The magnitude of the source is 19.0+/-0.2 (V-filter) and 18.8+/-0.2 (UVW1-filter) as determined by the Swift analysis tool, uvotsource. No optical afterglow is detected at the 3-sigma level in individual or coadded exposures in the UVOT UVW2-, UVM2-, U-, or B-filters. The 3-sigma limiting magnitudes for the coadded images of the UVOT filters are listed below: Filter T_range(s) Exp(s) Upper Limit (3-sigma) UVW2 551-6405 432 20.1 UVM2 463-10840 1366 20.4 U 511-12283 968 20.8 B 535-6199 422 20.6 where T_range is the start and end times of the coadded exposures. No correction has been made for Galactic reddening along the line of sight (E(B-V) = 0.16). No images were taken in the White-filter by the UVOT since bright stars were in the field-of-view.