TITLE: GCN CIRCULAR NUMBER: 16018 SUBJECT: GRB 140320A: Swift/UVOT Upper Limits DATE: 14/03/21 11:18:38 GMT FROM: Samantha Oates at MSSL S. R. Oates (UCL-MSSL) and J. K. Cannizzo (NASA/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 140320A 3723 s after the BAT trigger (Cannizzo et al., GCN Circ. 16000). No optical afterglow consistent with the enhanced XRT position (Page et al., GCN Circ 16011) 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 v 3723 5358 393 >19.2 b 4543 10186 1149 >20.8 u 4338 5973 393 >19.7 w1 4133 5768 393 >19.8 m2 3928 5563 393 >20.0 w2 3518 5153 393 >20.2 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.51 in the direction of the burst (Schlegel et al. 1998).