TITLE: GCN CIRCULAR NUMBER: 12821 SUBJECT: GRB 120106A: Swift/UVOT Upper Limits DATE: 12/01/09 14:10:13 GMT FROM: Stefan Immler at NASA/GSFC S. Immler (CRESST/GSFC/UMD) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 120106A 65 s after the BAT trigger (Immler et al., GCN Circ. 12810). No optical afterglow consistent with the XRT position (Evans et al., GCN Circ. 12813) 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 coadded exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 687 6326 451 >20.3 v 65 11570 619 >20.0 b 551 6736 452 >20.8 u 296 6531 924 >20.8 w1 678 6326 452 >20.3 m2 652 6121 454 >20.2 w2 603 11220 1239 >21.1 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 1.195 in the direction of the burst (Schlegel et al. 1998).