TITLE: GCN CIRCULAR NUMBER: 19496 SUBJECT: GRB 160601A: Swift/UVOT Upper Limits DATE: 16/06/03 15:28:24 GMT FROM: Mike Siegel at PSU/Swift MOC S. Sebzda (Penn State/Swift) and D. Kocevski (NASA/GSFC/ORAU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 160601A 78 s after the BAT trigger (Kocevski et al., GCN Circ. 19478). No optical afterglow consistent with the XRT position (Evans et al. GCN Circ. 19484) 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) 78 227 147 >21.00 white 78 589 166 >20.90 v 619 639 19 >17.30 b 544 564 19 >18.32 u (fc) 289 539 491 >20.19 uvw1 668 688 19 >17.72 uvm2 643 663 19 >17.46 uvw2 595 615 19 >17.87 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).