TITLE: GCN CIRCULAR NUMBER: 30526 SUBJECT: GRB 210725B: Swift/UVOT Upper Limits DATE: 21/07/27 00:38:22 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and M. G. Bernardini (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 210725B 92 s after the BAT trigger (Bernardini et al., GCN Circ. 30508). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 30510) 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 u (fc) 92 341 246 >20.5 b 347 439 91 >20.0 u 92 341 246 >20.5 w2 3722 3905 180 >19.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.023 in the direction of the burst (Schlegel et al. 1998).