[vsnet-grb-info 19211] GRB 170317A: MITSuME Okayama Ks-band upper-limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20892
SUBJECT: GRB 170317A: MITSuME Okayama Ks-band upper-limit
DATE:    17/03/17 16:39:39 GMT
FROM:    Kenshi Yanagisawa at OAO/NAOJ  <yanagi at oao.nao.ac.jp>

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 170317A (LaPorte et al., GCN 20885)
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 09:54 UT on 17th March, 8 min after
the BAT trigger, to 10:38 UT. The total exposure of 17.0 min
was successfully obtained.

In our co-add image, we did not find any new point source within
the XRT error circle (Beardmore et al., GCN 20887) down to
the limiting magnitude of Ks=16.1 (Vega, S/N=5). The photometric
calibration was made against 2MASS field stars.

T0+[sec]    MID-UT     T-EXP[sec]      Ks
---------------------------------------------------
   +1,819    10:16      1020.0          >16.1
---------------------------------------------------
T0+ : Elapsed time after the burt [sec]
T-EXP: Total Exposure time [sec]