TITLE: GCN CIRCULAR NUMBER: 12816 SUBJECT: INTEGRAL Weak trigger #6433: GRT Optical Observation DATE: 12/01/07 00:56:13 GMT FROM: Takanori Sakamoto at NASA/GSFC T. Sakamoto (UMBC/GSFC), D. Donato (UMD/GSFC), N. Gehrels (GSFC), T. Okajima (GSFC), Y. Urata (NCU) We observed the field of INTEGRAL Weak trigger #6433 with the 14-inch Goddard Robotic Telescope (GRT) located at the Goddard Geophysical and Astronomical Observatory (http://cddisa.gsfc.nasa.gov/ggao/). A total 242 good quality images of 5 sec (200 images) and 30 sec (42 images) exposures were taken in the R filter starting from Jan 6 05:11:52 (UT), about 58 seconds after the trigger (53 seconds after the notice), and stopped on Jan 6 06:08:10 (UT). We do not detect the optical afterglow both in the individual images and the stacked image inside the 3.65 arcmin error circle. The estimated five sigma upper limit of the combined image (total exposure of 2260 sec) is ~17.4 mag using the USNO-B1 catalog.