A. Fukui, Y. Itow, T. Sumi (STE Lab, Nagoya Univ.), and P. Tristram
(Canterbury Univ.) on behalf of the MOA Collabration (Bond et
al. 2001, Sumi et al. 2003) report:
We observed the optical afterglow of GRB080413A (GCN 7593, Rykoff &
Rujopakarn; GCN 7594, Beardmore et al.) on Apr. 13 between
12:29:16.4 UTC and 14:13:06.6 UTC, corresponding to about 9.5-11 h
after the burst, with the 1.8m MOA-II telescope at Mt. John
observatory in New Zealand. Total 5 images were obtained with a wide-
band Red filter (center wavelength ~ 750nm and FWHM ~ 250nm) and we
could identify the faint afterglow within the error circle (<0.5").
The identified R.A. Dec. are 19:09:11.752 -27:40:39.99 with an
uncertainty of 0.14" (radius, 1sigma) and following are the
photometric results: I magnitude = 20.24 +/- 0.32 at the mid-exposure
time of 2008-04-13 12:29:16.4 UTC, 20.09 +/- 0.19 at 12:51:10.7 UTC,
21.40 +/- 0.61 at 13:03:0.1 UTC, 20.05 +/- 0.17 at 13:42:47.0 UTC,
and 20.75 +/- 0.25 at 14:13:06.6 UTC. These photometry were done by
using the IRAF and calibrated against the USNO-B1.0 catalog stars,
and not corrected for the Galactic extinction.
[GCN OPS NOTE(18apr08): By the moderator's choice, the "GCN 7594, Stamatikos et al"
wash changed to "GCN 7594, Beardmore et al". Ack to F. Marshall.]