TITLE: GCN CIRCULAR NUMBER: 13698 SUBJECT: GRB 120821A: Swift/UVOT Upper Limits DATE: 12/08/22 11:38:06 GMT FROM: Samantha Oates at MSSL S. R. Oates (MSSL-UCL) and P. D'Avanzo (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 120821A 15ks after the INTEGRAL trigger (Mereghetti et al., GCN Circ. 13696). No optical afterglow consistent with the INTEGRAL position (Mereghetti et al., GCN Circ. 13696) 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 initial exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag u 17059 17241 179 >20.92 w1 16153 17053 886 >21.7 m2 15246 16146 886 >21.6 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 25.4 in the direction of the burst (Schlegel et al. 1998).