TITLE: GCN CIRCULAR NUMBER: 12540 SUBJECT: GRB 111107A: Swift/UVOT Afterglow Analysis DATE: 11/11/07 14:21:50 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (MSSL-UCL) and M. H. Siegel (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 111107A 73 s after the BAT trigger (Siegel et al., GCN Circ. 12534). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 73 223 147 19.45 +/- 0.10 v 615 1755 136 >18.7 b 540 1681 117 >20.0 u 285 1656 343 >19.9 w1 664 1631 117 >19.2 m2 639 5231 299 >19.7 w2 590 1730 136 >20.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.14 in the direction of the burst (Schlegel et al. 1998).