TITLE: GCN CIRCULAR NUMBER: 16368 SUBJECT: GRB 140606B: Swift/UVOT Upper Limits DATE: 14/06/09 02:46:27 GMT FROM: Margaret Chester at PSU M. M. Chester (PSU) and V. Mangano (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT observed the field of the Fermi/GBM-detected burst GRB 140606B beginning 184.4 ks after the Fermi/GBM trigger (Burns et al. GCN Circ. 16363). No source consistent with iPTF14bfu, the optical counterpart proposed by Singer et al. (GCN Circ. 16360) and Perley et al. (GCN Circ. 16365), 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) are given in the following table: Filter T_start(s) T_stop(s) Exp(s) Mag u 185271 191914 1693 >21.1 b 186146 192611 1495 >20.9 v 184395 191055 1693 >20.6 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).