[AAVSO-HEN] GRB 070610: MITSuME OAO optical upper limit

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
For an archive and more information on circulars visit:
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TITLE:   GCN CIRCULAR
NUMBER:  6512
SUBJECT: GRB 070610: MITSuME OAO optical upper limit
DATE:    07/06/12 07:07:28 GMT
FROM:    Michitoshi Yoshida at Okayama Astrophysical Obs  <yoshida at oao.nao.ac.jp>

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

We performed optical imaging observation (g', Rc, and Ic) of the
field of GRB 070610 (Pagani et al. GCN 6489) with 50cm MITSuME
telescope at Okayama Astrophysical Observatory from UT 12:27 to
UT 12:41 on Jun 11 2007.

We coadded 12 CCD frames for each band. Exposure time of each
frame is 1 minute. We made flux calibration using USNO B1.0
catalg. No new source was found at the position of the afterglow
candidate reported by A. de Ugarte Postigo (GCN 6501) and the XRT
source reported by Pagani et al. (GCN 6490). Three sigma limiting
magnitudes of our observation are listed below.

----------------------------------------------------
band   mid-UT          exp.time      upper limit
g'     Jun 11 12:34   12 x 1 min.    18.7 mag
Rc     Jun 11 12:34   12 x 1 min.    19.0 mag
Ic     Jun 11 12:34   12 x 1 min.    19.0 mag
----------------------------------------------------