TITLE: GCN CIRCULAR NUMBER: 14167 SUBJECT: GRB 130131B: MITSuME Okayama optical upper limits DATE: 13/02/01 01:00:50 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 130131B (Siegel et al., GCNC 14159) 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 19:11:04 UT (~57 sec after the burst). We did not find any new point source within the enhanced XRT circle (Goad et al., GCNC 14165) 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 ------------------------------------------------------ 0.03838 20:05:23 4800.0 >19.8 >19.9 >19.2 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]