TITLE: GCN CIRCULAR NUMBER: 19247 SUBJECT: GRB 160327A: Early RAPTOR Limits DATE: 16/03/29 22:58:53 GMT FROM: James Wren at LANL J. Wren, W.T. Vestrand, P. Wozniak, and H. Davis, of Los Alamos National Laboratory report: The RAPTOR network of robotic optical telescops made observations of Swift trigger 680655 (Racusin, et al., GCN 19235). Our Raptor-S telescope began imaging at 09:16:27.58 UT, 19.9 s after the Swift trigger time. We do not detect the optical counterpart reported by RATIR (Golkhou, et al., GCN 19236). We derive the following 3-sigma limits for our unfiltered observations based on comparison to the USNO-B1.0 catalog R-band. t-mid(s) exp(s) mag_limit ------------------------------- 32.5 5 17.4 67.8 40 18.6 131.8 10 18.0 180.4 100 19.2 249.9 200 19.6