TITLE: GCN CIRCULAR NUMBER: 19256 SUBJECT: GRB 160401A: Swift/UVOT Upper Limits DATE: 16/04/02 20:08:19 GMT FROM: Paul Kuin at MSSL Paul Kuin (MSSL/UCL) and L.M. McCauley (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 160401A 43ks s after the INTEGRAL trigger (Mereghetti et al., GCN Circ.19251). No optical afterglow consistent with the INTEGRAL position is detected in the initial UVOT exposures. The burst location was also observed by MASTER-IAC (Rebolo et al., GCN Circ. no. 19252); LT (Guidorzi et al. GCN Circ. no. 19254), and the Zadko observatory (Klotz et al. GCN Circ. 19255); none of whom observed an afterglow. 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 43678 44209 522 >20.8 v 44509 45370 843 >19.5 u 42847 43671 811 >19.9 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 1.13 in the direction of the burst (Schlegel et al. 1998). [GCN OPS NOTE(02apr16): The letter 'A' was added to the GRB name.]