GCN Circular 11817
F.E. Marshall (NASA/GSFC) and B. Sbarufatti (INAF-OAB/IASFPA) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 110319B 27685 s after the Fermi/GBM trigger (Cummings et al., GCN Circ. 11813). No optical afterglow consistent with the XRT position (Sbarufatti, GCN Circ. 11814) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the initial exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 28512 35117 1570 >21.8 v 29340 35964 1678 >20.0 u 27685 34323 1597 >20.8 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).