TITLE: GCN CIRCULAR NUMBER: 7622 SUBJECT: GRB 080413A: MOA-II optical afterglow observations DATE: 08/04/15 23:48:14 GMT FROM: Nobuyuki Kawai at Tokyo Tech 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.]