TITLE: GCN CIRCULAR NUMBER: 5696 SUBJECT: GRB061004: Swift/UVOT optical observations DATE: 06/10/05 11:38:35 GMT FROM: Samantha Oates at MSSL S. R. Oates (UCL-MSSL), H. Ziaeepour (UCL-MSSL) report on behalf of the Swift UVOT team The Swift Ultra-Violet/Optical Telescope (UVOT) began observations of GRB061004 at 19:51:14 UT, ~51 seconds after the initial Swift BAT trigger (Ziaeepour et al, GCN 5691). No optical counterpart was detected at the XRT position (Page et al, 6595) within the coadded images or with the V and white finding charts. The 3 sigma upper limits are provided for the coadded images and the finding charts below: Filter Start Stop Exposure 3SigmaUL -------------------------------------------------------- WHITE (finding) 68 168 100 18.4 V (finding) 174 574 400 20.0 V 704 24752 1477 18.9 B 652 13187 928 19.9 U 625 18969 1225 20.5 UVW1 604 18895 2121 21.2 UVM2 580 17988 1357 20.4 UVW2 680 24092 1337 20.5 WHITE 665 6706 520 20.3 -------------------------------------------------------- The values quoted above are not corrected for the expected Galactic extinction of E_{B-V}=0.049.