TITLE: GCN CIRCULAR NUMBER: 20581 SUBJECT: GRB 170202A: Kanata optical and infrared observations DATE: 17/02/02 23:12:08 GMT FROM: Michitoshi Yoshida at HASC,Hiroshima U Mori, H., Nakaoka, T., Kawabata, M., Hirochi, J., Kawahara, N., Yoshida, M., Kawabata, K. and Uemura, M. (Hiroshima Univ.) on behalf of the OISTER collaboration We performed R-band and Ks-band imaging observations around the error circle of GRB 170202A (Racusin et al., GCN 20575) with the optical imager HOWPol and opt-NIR imager HONIR attached to Kanata telescope of Hiroshima University. The observations took place at 2017-02-02 18:33:37 UT (mid time of the observation). We detected the optical transient reported by Xin et al.(GCN 20576), Lipunov et al. (GCN 20578) and Guidorzi et al. (GCN 20579) in our R-band and Ks-band images. The detected magnitude of the OT and five sigma upper limit (in Vega magnitude) of the observations are listed below. # T0+ MID-UT T-EXP R mag. R err R limit ----------------------------------------------------- 335 18:33:37 30 16.35 0.3 18.0 ----------------------------------------------------- # T0+ MID-UT T-EXP Ks mag. Ks err Ks limit ----------------------------------------------------- 3208 19:21:30 1320 17.1 0.4 18.6 ----------------------------------------------------- T0+ : Elapsed time after the burst [sec] T-EXP: Total Exposure time [sec]