TITLE: GCN CIRCULAR NUMBER: 32531 SUBJECT: GRB 220907A: Swift/UVOT Upper Limits DATE: 22/09/08 12:26:27 GMT FROM: Samantha Oates at MSSL S. R. Oates (U. Birmingham) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 220907A 95 s after the BAT trigger (Page et al., GCN Circ. 32526). No optical afterglow consistent with the enhanced XRT position (Page and Evans GCN Circ. 32530) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 95 245 147 >20.2 white 95 5001 298 >20.6 v 3823 4023 197 >18.6 b 4644 4844 197 >19.7 u 4438 4638 197 >19.4 w1 4234 4433 197 >19.2 m2 4028 4228 197 >19.2 w2 3618 3818 197 >19.2 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 1.637 in the direction of the burst (Schlegel et al. 1998).