TITLE: GCN CIRCULAR NUMBER: 18684 SUBJECT: GRB 151210A: Swift/UVOT Upper Limits DATE: 15/12/10 15:12:29 GMT FROM: Samantha Oates at MSSL S. R. Oates (IAA-CSIC/UCL-MSSL) and P. A. Evans (U Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 151210A 153 s after the BAT trigger (Evans et al., GCN Circ. 18678). No optical afterglow consistent with the optical position (Han et al., GCN Circ. 18679; Wiseman et al. GCN Circ. 18680) 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 153 302 147 >21.1 u_FC 311 560 246 >20.5 white 153 7227 805 >22.1 v 640 7549 442 >20.3 b 566 7023 510 >20.9 u 311 6817 736 >20.8 w1 690 6613 313 >20.4 m2 840 6407 235 >19.8 w2 616 7433 490 >20.7 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.12 in the direction of the burst (Schlegel et al. 1998).