[vsnet-grb-info 17044] GRB150915A : IRSF NIR upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18325
SUBJECT: GRB150915A : IRSF NIR upper limits
DATE:    15/09/17 01:58:08 GMT
FROM:    Daisuke Kuroda at OAO/NAOJ  <dikuroda at oao.nao.ac.jp>

K. L. Murata (Nagoya U.), S. Nagatomo (Kyoto U.), and T. Nagayama (Kagoshima U.)

We observed the field of GRB150915A (D'Elia et al., GCN Circular #18315) 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 2015-09-15 23:45:25 UT (~ 2.5 hours after the burst).
We could not detect the afterglow within the XRT error circle reported in the GCN circular in the three bands.
We have obtained the following preliminary upper limits (Vega magnitude system):

J  > 16.47
H  > 15.91
Ks > 15.64.

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 XRT position.

This observation was carried out by IRSF and OISTER collaboration.