TITLE: GCN CIRCULAR NUMBER: 19721 SUBJECT: GRB 160716A: Swift/UVOT Detection DATE: 16/07/18 00:25:59 GMT FROM: Lea Hagen at PSU L. M. Z. Hagen (PSU) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 160716A 88 s after the BAT trigger (Hagen et al., GCN Circ. 19716). A source consistent with the XRT position (Evans et al., GCN Circ. 19717) is detected in the initial UVOT exposures in the white filter. The source has marginal evidence for fading but is not seen in the Digitized Sky Survey (DSS), so it is unclear at this time whether it is the optical afterglow. Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 88 773 183 19.93+-0.23 white 6218 6418 196 20.47+-0.35 white 24012 98905 490 20.62+-0.25 v 631 651 19 >17.58 b 556 750 38 >18.95 u 301 725 265 >19.63 uvw1 681 701 19 >17.48 uvm2 656 676 19 >17.10 uvw2 607 627 19 >17.52 The magnitudes in the table are not corrected for the Galactic extinction due to the large, but uncertain, reddening of E(B-V) = 1.47 in the direction of the burst (Schlegel et al. 1998).