TITLE:   GCN CIRCULAR
NUMBER:  18408
SUBJECT: GRB 151006A: MITSuME Okayama Ks-band upper-limit
DATE:    15/10/07 02:58:46 GMT
FROM:    Kenshi Yanagisawa at OAO/NAOJ  <yanagi@oao.nao.ac.jp>

Kenshi Yanagisawa, Daisuke Kuroda, Yasuhiro Shimizu,
Hideyuki Izumiura(OAO/NAOJ), Michitoshi Yoshida (Hiroshima-U),
Kouji Ohta(Kyoto-U) and Nobuyuki Kawai(Tokyo Tech.) report
on behalf of the MITSuME collaboration:

We observed the field of GRB151006A (Kocevski et al., GCN 18398)
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 17:22 UT on 6th October, 7.4h after
the BAT trigger, to 18:17 UT. The total exposure of 26.5 min
was successfully obtained.

In our co-add image, we did not find any new point source within
the enhanced XRT error circle (Goad et al., GCN 18403) down
to limiting magnitude of Ks=15.2 (Vega, S/N=10). The photometric
calibration was made against 2MASS field stars.

T0+[sec]    MID-UT     T-EXP[sec]      Ks
---------------------------------------------------
 +26,819    17:49      1,590           >15.2
---------------------------------------------------
T0+ : Elapsed time after the burt [sec]
T-EXP: Total Exposure time [sec]