TITLE: GCN CIRCULAR NUMBER: 15861 SUBJECT: GRB 140215A: RAPTOR Observations During Gamma-Ray Emitting Interval DATE: 14/02/19 15:35:54 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 telescopes made follow-up observations of Swift trigger 586680 (Markwardt, et al., GCN 15837). Our narrow-field instruments in Los Alamos, NM, began imaging at 04:07:37.21 UT, 26.9 seconds after the BAT trigger time. We do not detect the counterpart in our three initial images, with limiting magnitudes near 14.0. The counterpart then rises above our detection limit and reaches peak brightness at magnitude 13.5 around T-Tbat=90s. The counterpart then plateaus for a period of about 50 seconds before beginning a power-law decay. Our unfiltered observations were calibrated to the USNO-B1 R-band. The following table summarizes some of our early observations. t-mid(s) exp(s) mag error ------------------------------------ 29.45 5 >14.0 56.85 5 13.8287 0.033 83.85 5 13.5381 0.011 128.95 10 13.5608 0.008 283.35 10 14.3725 0.024 470.75 30 14.9185 0.020