TITLE: GCN CIRCULAR NUMBER: 22857 SUBJECT: GRB 180626A: Swift/UVOT Detection DATE: 18/06/26 15:22:56 GMT FROM: Alice Breeveld at MSSL-UCL A. A. Breeveld (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 180626A 123 s after the BAT trigger (Evans et al., GCN Circ. 22850). A fading source consistent with the XRT position (Osborne et al. GCN Circ. 22852) and also seen by Martone et al. (GCN Circ. 22854) and Troja et al. (GCN Circ. 22855) is detected in the initial UVOT exposures. Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the finding chart (FC) and early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 123 273 147 20.57 ± 0.22 white 633 1033 190 >21.4 v 665 6473 452 >20.2 b 591 5858 246 >20.4 u 336 6936 529 >20.7 w1 714 6882 432 >21.0 m2 5043 6677 393 >20.1 w2 641 6268 432 >21.3 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).