TITLE: GCN CIRCULAR NUMBER: 18819 SUBJECT: GRB 160104A: MITSuME Okayama Ks-band upper-limit DATE: 16/01/04 14:10:03 GMT FROM: Kenshi Yanagisawa at OAO/NAOJ K. Yanagisawa, D. Kuroda, Y. Shimizu, H. Izumiura(OAO/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 160104A (Melandri et al., GCN 18815) in Ks-band with a wide-field near infrared imager at Okayama Astrophysical Observatory (Japan). The imager has effective aperture of 0.91 m. Observations started from 11:46 UT on 4th January, 0.38h after the BAT trigger, to 12:49 UT. The total exposure of 24.0 min was successfully obtained. In our co-add image, we did not find any new point source within the XRT error circle down to the limiting magnitude of Ks=16.8 (Vega, S/N=3). The photometric calibration was made against 2MASS field stars. T0+[sec] MID-UT T-EXP[sec] Ks --------------------------------------------------- +3,235 12:18 1440.0 >16.8 --------------------------------------------------- T0+ : Elapsed time after the burt [sec] T-EXP: Total Exposure time [sec]