TITLE: GCN CIRCULAR NUMBER: 7758 SUBJECT: GRB080520: Swift/UVOT observations DATE: 08/05/21 13:12:58 GMT FROM: Samantha Oates at MSSL S.R. Oates (MSSL/UCL) and D. Grupe (PSU) report on behalf of the Swift/UVOT team The Swift/UVOT began settled observations of the field of GRB 080520, 105s after the BAT trigger (Grupe et al., GCN 7753). We detect the afterglow in the white, v filters at the position: RA(J2000.0) = 18:40:46.30 DEC(J2000.0) = -54:59:31.0 with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence). This position is consistent with the UVOT enhanced XRT position (Goad et al., GCN 7755). UVOT magnitudes and 3 sigma upper limits are reported below for the single and coadded images: Filter Tstart(s) Tstop Expo(s) Magnitude/3sigUL ----------------------------------------------------- white 105 204 98 19.59 +/- 0.12 white 858 958 98 20.58 +/- 0.28 v 211 610 400 20.26 +/- 0.38 v 964 1299 330 19.96 +/- 0.45 b 691 6273 216 > 20.92 u 666 6068 197 > 20.60 w1 641 5862 236 > 20.33 m2 617 7079 418 > 20.38 w2 720 6684 216 > 20.25 ----------------------------------------------------- These magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E{B-V} = 0.08 mag (Schlegel et al. 1998). The photometry is on the UVOT flight system described in Poole et al. (2008, MNRAS, 383, 627).