TITLE: GCN CIRCULAR NUMBER: 6746 SUBJECT: GRB070810B: Optical observations with KANATA DATE: 07/08/10 17:34:52 GMT FROM: Makoto Uemura at Hiroshima U M. Uemura, A. Arai, O. Nagae, and T. Uehara (Hiroshima Univ.), report on behalf of the KANATA GRB team: We started optical imaging of the field of GRB070810B (GCN 6743) at 15:22:37 UT 10 Aug. using TRISPEC attached to the KANATA 1.5-m telescope at Higashi-Hiroshima Observatory, Japan. Exposure times are 30 sec for the first 10 frames, then changed to 123 sec for late frames. We have performed preliminary analysis for the first 30-min images. No new bright object was detected. There is no object showing significant fadings. Limit magnitudes are estimated from neighbour USNO A2.0 stars as follows: 10 Aug. UT limit mag. band 15:33:22 20.8 Rc 15:55:04 20.9 Rc We note that there is a possible minor planet at RA=00:35:59.3, Dec=+08:50:15 (time=15:33:22 UT). The object is about Rc=20.1, and moving northward during our observations.