TITLE: GCN CIRCULAR NUMBER: 17790 SUBJECT: GRB 150430A: Swift/UVOT Upper Limits DATE: 15/04/30 09:49:53 GMT FROM: Samantha Oates at MSSL S. R. Oates (IAA-CSIC/UCL-MSSL) and V. D'Elia (ASDC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150430A 115 s after the BAT trigger (D'Elia et al., GCN Circ. 17789). No optical afterglow consistent with the XRT position 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 115 265 147 >20.6 u_FC 273 523 246 >19.7 white 115 5422 344 >21.2 v 4196 5832 393 >19.8 b 5017 6487 231 >20.3 u 273 6447 639 >20.3 w1 4607 6242 393 >20.4 m2 4401 6037 393 >20.7 w2 3990 5627 393 >20.9 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).