TITLE: GCN CIRCULAR NUMBER: 22836 SUBJECT: GRB 180624A: Swift/UVOT Upper Limits DATE: 18/06/24 22:33:42 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and S. L. Gibson (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 180624A 118 s after the BAT trigger (Gibson et al., GCN Circ. 22832). No optical afterglow consistent with the XRT position (Gibson et al. GCN Circ. 22832) 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 118 268 147 >20.7 u_FC 276 526 246 >19.4 white 118 6151 541 >21.3 v 4927 6395 229 >20.0 b 4312 5947 393 >21.2 u 276 5742 639 >20.6 w1 3902 5537 393 >20.2 m2 5132 5332 197 >19.7 w2 4723 6357 393 >20.8 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.05 in the direction of the burst (Schlegel et al. 1998).