TITLE: GCN CIRCULAR NUMBER: 19801 SUBJECT: GRB 160815A: Swift/UVOT Detection DATE: 16/08/16 21:53:24 GMT FROM: Mike Siegel at PSU/Swift MOC S.J. LaPorte (PSU) and C. B. Markwardt (NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 160815A 90 s after the BAT trigger (Markwardt et al., GCN Circ. 19794). We detect a fading source consistent with the XRT position (Beardmore et al. GCN Circ. 19796). Preliminary detections 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 90 239 146 18.17+-0.14 white 582 5549 402 >19.72 v 632 5960 274 >17.99 b 557 5344 254 >18.64 u 301 6449 554 >18.85 uvw1 681 6370 432 >18.67 uvm2 656 6165 274 >18.64 uvw2 607 5755 274 >18.70 The magnitude is not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.12 in the direction of the burst (Schlegel et al. 1998).