TITLE: GCN CIRCULAR NUMBER: 15389 SUBJECT: Swift Trigger 575905/ GRB 131026A: MITSuME Okayama and Ishigakijima Optical upper limits DATE: 13/10/27 11:07:44 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, (OAO, NAOJ), H. Hanayama (IAO, NAOJ), K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), T. Miyaji J. Watanabe, (IAO, 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 1301026A (Swift Trigger 575905) (Cenko et al., GCNC 15384) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory and the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory. We did not find any new point source within the BAT error circle (Cenko et al., GCNC 15384) in all the three bands. Three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for flux calibration. Okayama Astrophysical Observatory: The observation started on 2013-10-26 10:01:09 UT (~3.4 h after the burst). T0+[day] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------ 0.24326 12:29:49 6300.0 >19.7 >19.6 >18.6 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] Ishigakijima Astronomical Observatory: The observation started on 2013-10-26 13:13:44 UT (~6.6 h after the burst). T0+[day] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------ 0.30110 13:53:07 3360.0 >21.6 >21.0 >20.4 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]