TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1689 SUBJECT: GRB 021112: RAPTOR Observations DATE: 02/11/13 23:21:48 GMT FROM: James Wren at LANL J. Wren, W. T. Vestrand, K. Borozdin, S. Brumby, D. Casperson, M. Galassi, K. McGowan, D. Starr, R. White, and P. Wozniak report: One of our RAPTOR (RAPid Telescopes for Optical Response) wide-field telescope arrays responded to the HETE-2 alerts for GRB 021112 (trigger #2448). That array, located in Los Alamos, New Mexico, is composed of four Canon 85 mm f1.2 telephoto lenses, which together image approximately 1300 squares degrees, and a central "fovea" telescope employing a 400 mm f2.8 Canon telephoto lens that images a central 16 square degree field. An unfiltered Apogee AP-10 CCD camera is located at the focal plane of each telescope. Mosaic imaging of the HETE-2 field-of-view began at 3:29:01 UTC, just 45.4 s after the GRB trigger. All of the images of the burst location taken before the GRB position was released place the location of the burst just 100 pixels from the edge of the imager where vignetting causes a significant loss of sensitivity. The image sensitivity was further reduced by thin cirrus clouds which were apparent in all of the early images. No new objects were detected within the HETE-2 error circle after comparison with archival images. The following limits were obtained for the initial response images: Exposure Time since Exposure Limiting Imager start time trigger duration Magnitude (UTC) (minutes) (seconds) (5 sigma) --------------------------------------------------------------- 3:29:56 1.67 5 11.4 wide-field 3:32:49 4.55 30 11.7 wide-field 4:49:44 81.46 30 14.6 fovea This message is citable.