TITLE: GCN CIRCULAR NUMBER: 12226 SUBJECT: GRB110731A: MITSuME Ishigakijima Optical Upper Limits DATE: 11/08/01 14:10:02 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ), K. Yanagisawa (OAO, NAOJ), S.Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 110731A (Oates et al., GCNC 12215) with the optical three color (g', Rc and Ic) CCD camera attached to the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory. The observation started on 13:02:23 UT (~1.9 h after the burst). We did not find any new point source within the enhanced XRT error circle (Beardmore et al., GCNC 12219) in all the three bands. We could not detect the previously reported afterglow (Bersier, GCNC 12216; Malesani et al., GCNC 12220). Three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' Rc Ic ---------------------------------------------------- 0.12025 14:02:40 6180.0 >21.8 >20.6 >20.1 ---------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]