TITLE: GCN CIRCULAR NUMBER: 10679 SUBJECT: GRB100424A: MITSuME optical upper limits DATE: 10/04/25 08:14:00 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 100424A (Hoversten et al. GCNC 10667) 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 2010-04-24 16:34:56 UT (~2.2 min after the burst). We did not find any new point source within the XRT error circle (Evans, GCNC 10668; Evans et al., GCNC 10669) 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 ------------------------------------------------------ 0.00527 16:40:18 540.0 >18.4 >18.5 >17.7 0.04356 17:35:26 5940.0 >19.6 >20.0 >19.4 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]