TITLE: GCN CIRCULAR NUMBER: 6378 SUBJECT: GRB070506: Swift/UVOT Observations DATE: 07/05/07 02:58:56 GMT FROM: Wayne Landsman at GSFC/SSAI W. Landsman (SSAI/GSFC) and C. Pagani (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began taking data in the field of GRB070506 459s after the BAT trigger (Pagani et al., GCN 6375). A fading afterglow is weakly detected in the White, B and V UVOT filters, but not in the U or UV filters. We use the combined white image to obtain an improved position of RA(J2000) = 23h 08m 52.39s Dec(J2000) = +10d 43' 20.8" with a 1-sigma uncertainty radius of about 0.5". This is 0.5" from the UVOT position reported by Pagani et al. (GCN 6375) and 2.9" from the refined XRT position reported by Pagani et al. (GCN 6377). Photometry results are given for the 7 UVOT filters below. Tstart Tstop Exp Mag White 459 558 98 19.7+/-0.18 868 967 98 19.9+/-0.22 7371 7570 196 20.4+/-0.28 V 974 1373 393 19.1+/-0.2 7781 7980 197 >19.3 (3 sigma) B 638 2245 136 19.8+/-0.34 7167 7366 197 >20.4 (3 sigma) U 638 5853 261 >20.1 (3 sigma) UVW1 614 5741 352 >20.4 (3-sigma) UWM2 7984 8142 155 >19.6 (3-sigma) UVW2 840 7775 294 >20.4 (3-sigma) No correction has been made for the expected Galactic reddening of E(B-V)=0.04