TITLE: GCN CIRCULAR NUMBER: 12024 SUBJECT: GRB 110520A: Skynet/DAO optical observations DATE: 11/05/20 23:03:37 GMT FROM: Aaron LaCluyze at U.North Carolina A. LaCluyze, M. Maturi, K. Ivarsen, J. Haislip, D. Reichart, J. Moore, A. Trotter, A. Foster, R.Egger, A. Oza, E. Speckhard, J. A. Crain, and M. Nysewanderreport: Skynet observed the Swift/XRT localization of GRB 110520A (Swift trigger#453747) with the Dolomites Astronomical Observatory located at the Carlo Magno Hotel Spa Resort in Italy. Due to local twilight, observations in SDSS g',r',i' and z' did not begin until ~25 minutes after the trigger. We do not detect an optical transit within the Swift error circle in any filter. Our earliest time photometry yields the following 3-sigma limiting magnitudes: g' 17.8 (mean time of 26.78 minutes after trigger), r' 19.7 (mean time of 31.32 minutes after trigger, two combined exposures), i' 18.5 (mean time of 37.10 minutes after trigger, two combined exposures), z' 17.8 (mean time of 41.95 minutes after trigger) based on comparison ~6 nearby SDSS sources. This message may be cited.