GCN Circular 15815
J. Wren, W.T. Vestrand, P. Wozniak, and H. Davis, of Los Alamos National Laboratory report: The RAPTOR network of robotic optical telescopes made follow-up observations of Swift trigger 586071 (Cenko, et al., GCN 15808). Our narrow-field instruments in Los Alamos, NM, began imaging at 07:31:24.33 UT, 26.5 seconds after the BAT trigger time. We clearly detect the optical counterpart (Perley, et al., GCN 15809). Our first image at Tmid-Tbat=29.0s shows the counterpart at an unfiltered magnitude of 14.43+-.04. The counterpart fades steadily to mag 15.50+-.08 by Tmid-Tbat=65.4s. Our unfiltered observations were calibrated to the USNO-B1 R-band.