TITLE: GCN CIRCULAR NUMBER: 12814 SUBJECT: GRB 120106A: MITSuME Okayama Optical upper limits DATE: 12/01/06 23:03:34 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (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 120106A (Immler et al., GCNC 12810) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory. The observation started on 2012-01-06 14:17:12 UT (~48 sec after the burst). We did not find any new point source within the enhanced XRT circle (Evans et al., GCNC 12813) in all the three bands. 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 ------------------------------------------------------ 0.00400 14:22:10 540.0 >19.3 >19.4 >18.7 0.04247 15:17:33 6420.0 >20.6 >20.2 >19.6 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]