TITLE: GCN CIRCULAR NUMBER: 18278 SUBJECT: GRB 150910A: MITSuME Okayama Ks-band Observation DATE: 15/09/11 09:07:35 GMT FROM: Kenshi Yanagisawa at OAO/NAOJ Kenshi Yanagisawa, Daisuke Kuroda, Yasuhiro Shimizu, Hideyuki Izumiura (OAO/NAOJ), Michitoshi Yoshida (Hiroshima-U), Kouji Ohta(Kyoto-U), and Nobuyuki Kawai(Tokyo Tech.) report on behalf of the MITSuME collaboration: We observed the field of GRB150910A (Pagani et al., GCNC 18264) in Ks-band with a wide-field NIR camera at Okayama Astrophysical Observatory (Japan). The camera has an effective aperture of 0.91m. Observations started from 10:03 UT on 10th September, 59 min after the BAT trigger, to 11:14 UT. The total exposure of 26 min was successfully obtained. In our co-add image, we found a single point source at R.A.(J2000) = 00:22:39.84 DEC (J2000) = +33:28:20.5 with an uncertainty of of about 2 arcsec. We estimate the magnitude Ks = 14.85 +/- 0.13 (Vega). The calibration was made against 2MASS field stars. T0+[min] MID-UT T-EXP[min] Ks ------------------------------------------------------------ +94 10:38 26 14.85 +/- 0.13 (Vega) ------------------------------------------------------------ T0+ : Elapsed time after the burst [min] T-EXP: Total Exposure time [min]