[vsnet-grb-info 19125] GRB 170208A: IRSF upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20672
SUBJECT: GRB 170208A: IRSF upper limits
DATE:    17/02/14 07:27:20 GMT
FROM:    Katsuhiro L. Murata at Nagoya U  <murata at u.phys.nagoya-u.ac.jp>

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.