[vsnet-grb-info 7613] GRB 090418: Optical observations with MITSuME Okayama and Ishigaki 1m telescope

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9168
SUBJECT: GRB 090418: Optical observations with MITSuME Okayama and Ishigaki 1m telescope
DATE:    09/04/20 07:23:37 GMT
FROM:    Michitoshi Yoshida at Okayama Astrophysical Obs  <yoshida at oao.nao.ac.jp>

D. Kuroda, M. Yoshida, M. Isogai, K. Yanagisawa, Y. Shimizu,
S. Nagayama, H. Toda, M. Isogai (NAOJ) and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 090417B (Mangano et al. GCN 9149)
with optical three color (g', Rc and Ic) CCD cameras attached to
the MITSuME 50cm telescope of Okayama Astrophysical Observatory
and the 1m telescope of Ishigaki-Jima Observatory.

We started the observation at 13:26:42 UT, 8342s after the burst
at Okayama. We could not find a new source at the position of the
afterglow (Chornock et al. GCN 9148; Mangano et al. GCN 9149;
Goad et al. GCN 9154). 3-sigma upper limits to our observations
are the following. We used GSC2.3 catalog for flux calibration.

Okayama MITSuME observation
 Mid-UT     Td(day)         EXP-T          g'     Rc     Ic
-------------------------------------------------------------
13:56:41    0.11736    2940s (49x60s)     >19.2  >19.1  >19.0
16:27:25    0.22204    5880s (98x60s)     >20.5  >20.3  >20.1
-------------------------------------------------------------

Ishigaki-Jima 1m telescope observation
 Mid-UT     Td(day)         EXP-T          g'     Rc     Ic
-------------------------------------------------------------
14:48:36    0.15342    3000s (10x300s)    >20.6  >20.9  >19.9
-------------------------------------------------------------