TITLE: GCN CIRCULAR NUMBER: 22730 SUBJECT: GRB 180510A: MITSuME Ishigakijima optical upper limits DATE: 18/05/15 01:02:37 GMT FROM: Ryosuke Itoh at Tokyo Institute of Tech. T. Horiuchi, H. Hanayama, M. Honma (IAO, NAOJ), R. Itoh, K. L. Murata and N. Kawai (Tokyo Tech) report on behalf of the MITSuME and OISTER collaboration: We observed the field of GRB 180510A (Gropp et al.,GCN 22695) with the optical three color (g', Rc and Ic) CCD camera attached to the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory. The observation started on 2018-05-10 19:29:21 UT, (287 seconds after the burst). No new or fading source is detected within the Swift-XRT error circle. We note that there is faint (~20mag) source detected in DSS images within XRT error circle (at 18:25:19.2, -31:54:22.7) but the source did not shows temporal variability during observation (~45 min). we derive the following upper limits using UCAC-4 catalog for flux calibration. #T0+[sec] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------------------- 287 19:55:17 2700.0 >19.4 >20.4 >20.2 ------------------------------------------------------------------- T0+ : Elapsed time after the burst [hour] T-EXP: Total Exposure time [sec]