GCN Circular 20672
K. L. Murata (Nagoya U), L. Townsend (UCT), I. Monageng (SAAO), Y. Moritani (Kavli IPMU), M. Jian (U of Tokyo), S. Chimasu (Tokai U), A. Kawachi (Tokai U), A. Okazaki (Hokkai-Gakuen U) and T. Nagayama (Kagoshima U) We observed the field of GRB 170208A (Cholden-Brown et al., GCN Circular #20631) with the near-infrared (J, H, Ks) simultaneous imaging camera SIRIUS attached to 1.4 m telescope IRSF (InfraRed Survey Facility) in Sutherland observatory, South Africa. The observations started on 2017-02-08 18:56:55 UT (~ 43 min. after the burst). We could not detect the afterglow within the enhanced XRT error circle (Evans et al., GCN Circular #20634) in the three bands. We have obtained the following preliminary upper limits (Vega magnitude system): J > 16.50 H > 16.25 Ks > 15.92 Given magnitudes were calibrated against 2MASS point sources in this field. The upper limits were determined as the magnitudes of the faintest star within 1 arcmin from the enhanced XRT position. This observation was carried out by IRSF and OISTER collaboration.