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GCN Circular 9892

GRB 090904B: MOA-II Optical observation
2009-09-04T15:29:08Z (15 years ago)
Kenta Nishimoto at Nagoya U/MOA-II <>
K. Nishimoto, T. Sako, and D. Suzuki (STE Lab, Nagoya Univ.)
on behalf of the MOA Collaboration  report:

We searched for an optical afterglow of GRB090904B (GCN9881, V. D'Elia
et al.) starting from 07:34:56.9 UT on 2009 Sep 4 (6 hours after the
burst) with the MOA-II 1.8m telescope at Mt.John observatory in New Zealand.
In a single image of a 60 sec exposure with a wideband Red filter
(center wavelength ~ 750nm and FWHM ~ 250nm), we did not find any object
within the error circle of the Swift XRT source position (GCN 9887),
except a USNO-B1.0 catalog star, 0647-0516939, which has I mag=15.10 and
the separation of 1.8 arcsec from the center of the position.

Quick estimation of the limiting magnitude is >20.5 calibrated by using
USNO-B1.0 catalog.
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