TITLE: GCN CIRCULAR NUMBER: 23345 SUBJECT: GRB 181011A: MITSuME Akeno and Okayama optical upper limits DATE: 18/10/17 10:02:24 GMT FROM: Adachi Ryo at Tokyo Institute of Tech R. Adachi, R. Itoh, K. L. Murata, Y. Tachibana, K. Morita, K. Shiraishi, K. Iida, M. Oeda, M. Niwano, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We performed tiling observation for error region of GRB 181011A (Kawakubo et al., GCN Circular #23327) with the optical three color (g', Rc, and Ic) CCD cameras attached to the two MITSuME 50cm telescopes at Akeno Observatory and Okayama Astrophysical Observatory, in Japan. The observation started on 2018-10-12 13:51:34 UT. Our tiling observation covers about 90% of MAXI error region. We did not find any point source at the position of the MAXI error box (Kawakubo et al., GCN Circular #23327) in all three bands. Unfortunately, thin cloud were passing during the observation therefore we could not obtain uniform exposure for each data set between tiling. Finally we obtained following 5-sigma upper limits for the magnitudes 35% region: g' > 18.0, Rc > 17.7, Ic > 17.0 40% region: g' > 16.5, Rc > 16.2, Ic > 15.7 15% region: g' > 15.0, Rc > 14.7, Ic > 14.2 We used UCAC-4 catalog for flux calibration.