TITLE: GCN CIRCULAR NUMBER: 30619 SUBJECT: GRB 210807C: Swift/UVOT Upper Limits DATE: 21/08/08 21:44:40 GMT FROM: Sam LaPorte at PSU GRB 210807C: Swift/UVOT Upper Limits S. J. LaPorte (PSU) and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 210807C 180 s after the BAT trigger (Lien et al., GCN Circ. 30610). No optical afterglow consistent with the XRT position (Lien et al. GCN Circ. 30610) 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 initial exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag v 180 852 596 >19.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 3.076 in the direction of the burst (Schlegel et al. 1998).