GCN Circular 22309
N.P.M. Kuin (UCL-MSSL) and A..P. Beardmore (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT performed observations of the field of GRB 180103A (Beardmore et al. GCN Circ. 22305). No optical afterglow consistent with the XRT position (Melandri et al. GCN. Circ. 22308) is detected in the UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) are: Filter T_start(ks) T_stop(ks) Exp(s) Mag v 344.2 350.7 1044 >19.9 u 344.2 350.7 848 >20.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.48 in the direction of the burst (Schlegel et al. 1998).