TITLE: GCN CIRCULAR NUMBER: 7693 SUBJECT: GRB080506: Swift/UVOT observations DATE: 08/05/07 16:22:15 GMT FROM: Samantha Oates at MSSL S.R. Oates (MSSL/UCL) and W. Baumgartner (NASA/GSFC) report on behalf of the Swift/UVOT team The Swift/UVOT began settled observations of the field of GRB 080506, 143s after the BAT trigger (Baumgartner et al., GCN 7685). We detect the afterglow in the v and b filters at the position: RA(J2000.0) = 21:57:41.84 DEC(J2000.0) = +38:59:06.1 with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence). This position is consistent with the UVOT enhanced XRT position (Osborne et al., GCN 7687) and the TLS position (Kann et al., GCN 7688). No observations were performed with the white filter due to the presence of 7.5mag B star (HD 208837) 6 arcmins from the GRB position. UVOT magnitudes and 3 sigma upper limits are reported below for the single and coadded images: Filter Tstart(s) Tstop Expo(s) Magnitude/3sigUL ----------------------------------------------------- v 143 543 393 18.35 +/- 0.10 v 6728 6928 197 19.88 +/- 0.52 b 623 771 19 19.84 +/- 0.65 (1.7-sigma) b 10818 11118 295 20.64 +/- 0.28 (3.8-sigma) u 599 6311 254 > 20.29 w1 574 7338 471 > 20.44 m2 1284 7133 787 > 20.69 w2 639 6723 432 > 20.46 ----------------------------------------------------- These magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E{B-V} = 0.23 mag (Schlegel et al. 1998). The photometry is on the UVOT flight system described in Poole et al. (2008,MNRAS,383,627).