TITLE: GCN CIRCULAR NUMBER: 14166 SUBJECT: GRB 130131A: MITSuME Okayama optical upper limits DATE: 13/02/01 00:50:07 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 130131A (Grupe et al., GCNC 14156) 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 2013-01-31 14:53:53 UT (~58 min after the burst). We did not find any new point source within the enhanced XRT circle (Evans et al., GCNC 14160) in all the three bands. Three sigma upper limits of the OT are listed below. We used SDSS catalog for flux calibration. T0+[day] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------ 0.10111 16:21:58 9000.0 >20.5 >20.5 >19.9 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]