GCN Circular 9541
M. Im (CEOU/Seoul National Univ), Y.-B. Jeon (KASI), and Y. Urata (NCU) We observed GRB090618 (Schady et al. GCN 9512) in V using a 15.5cm refractor at Bohyunsan Optical Astronomical Observatory in Korea, operarted by the Korea Astronomy Space Science Institute. A series of exposures were taken starting at 2009 June 18, 11:54:19. The afterglow, identified earlier by many groups (GCN 9513, 9514, 9515, 9520, 9522), was clearly detected at V=17.9 +- 0.1 magnitude at mid-time of 2009 12:55:07 (about 4hr 26.6min after the BAT trigger). The photometry was calibrated against nearby SDSS stars where the transformation of SDSS magnitude to V-band magnitude was carried out using the recipe of Chonis & Gaskell (2008).