TITLE: GCN CIRCULAR NUMBER: 13924 SUBJECT: GRB 121028A: RAPTOR Limits During Gamma-Ray Emitting Interval DATE: 12/10/29 16:05:04 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 observations of Swift trigger 536897 (Starling, et al., GCN 13913). The burst location was within the field of our wide-field monitor located in Maui, HI, which began a 10 s integration of the location at 05:04:32.5 UT, 0.6 s after the Swift trigger time and during the gamma-ray emitting interval including the time of peak emission detected by the BAT (Sakamoto, et al., GCN 13917). We detect no new object at the location of the refined Swift XRT location (Evans, et al., GCN 13918). Our 3-sigma limiting magnitude is 10.0 based on a comparison of our unfiltered image to the Tycho-2 V-band catalog.