TITLE: GCN CIRCULAR NUMBER: 24943 SUBJECT: GRB 190630B: Swift/UVOT Upper Limits DATE: 19/07/01 17:59:50 GMT FROM: Kira Simpson at PSU GRB 190630B: Swift/UVOT Upper Limits K. K. Simpson (PSU) and F. E. Marshall (NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 190630B 65 s after the BAT trigger (Krimm et al., GCN Circ. 24913). No optical afterglow consistent with the optical position (Zheng and Filippenko GCN Circ. 24914) 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 white 65 131 65 >20.5 b 57357 57675 308 >20.69 uvm2 39177 40077 885 >20.36 u 46044 46193 145 >19.89 v 55313 55640 317 >18.87 uvw1 40084 40453 363 >20.02 uvw2 49543 49700 155 >19.09 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998).