TITLE: GCN CIRCULAR NUMBER: 30730 SUBJECT: GRB 210824A: Swift/UVOT Upper Limits DATE: 21/08/27 15:52:44 GMT FROM: Sam LaPorte at PSU GRB 210824A: Swift/UVOT Upper Limits S. J. LaPorte (PSU) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 210824A 311 s after the BAT trigger (Page et al., GCN Circ. 30700). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 30702) 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 311 461 147 >20.8 white 311 4350 364 >20.9 v 467 4760 236 >19.4 b 565 4145 235 >20.1 u 541 5220 83 >19.6 w1 516 5170 236 >20.4 m2 4765 4965 197 >20.3 w2 4356 4555 197 >19.9 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.037 in the direction of the burst (Schlegel et al. 1998).