TITLE: GCN CIRCULAR NUMBER: 12984 SUBJECT: GRB 120224A: Swift/UVOT Upper Limits DATE: 12/02/24 16:39:22 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (MSSL-UCL) and C. J. Saxton (UCL-MSSL) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 120224A 115 s after the BAT trigger (Saxton et al., GCN Circ. 12980). No optical afterglow consistent with the enhanced XRT position (Osborne et al., GCN Circ. 12981) 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 115 264 147 >20.7 u_FC 273 522 246 >20.5 white 115 1547 392 >21.2 v 602 1424 97 >19.4 b 529 1522 97 >20.2 u 273 1497 304 >20.4 w1 1107 1127 19 >19.6 m2 1254 1448 39 >19.8 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998).