GCN Circular 12354
F. E. Marshall (NASA/GSFC) and J. K. Cannizzo (GSFC/UMBC/CRESST) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 110915B 36,747 s after the AGILE trigger (Del Monte et al., GCN Circ. 12341). No optical afterglow consistent with the position of the X-ray (D'Avanzo et al. GCN Circ.12348) or optical (de Ugarte Postigo et al., GCN Circ. 12350) afterglow candidates 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 37077 48670 1468 >22.2 v 42882 48935 542 >20.1 u 36747 52898 1869 >22.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.07 in the direction of the burst (Schlegel et al. 1998).