TITLE: GCN CIRCULAR NUMBER: 6531 SUBJECT: GRB070612A: MITSuME Okayama Observation DATE: 07/06/13 23:25:29 GMT FROM: Michitoshi Yoshida at Okayama Astrophysical Obs 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 observations (Rc and Ic) of the field of GRB 070612A (Grupe et al., GCN 6509) with 50cm MITSuME telescope at Okayama Astrophysical Observatory from UT 11:19 to UT 11:27 on June 12 2007. We coadded 4 CCD frames for each band. Exposure time of each frame is 1 minute. We made flux calibration using USNO B1.0 catalg. We found a faint source at the position of the afterglow candidate reported by Cenko et al. (GCN 6525, RA:08:05:29.6, DEC:+37:16:15) in Ic band. The Ic magnitude was 17.1 +/- 0.3. There was no source brigher than 16.7 magnitude in Rc band. Flux calibration was made with three USNO-B stars around the object. --------------------------------------------------------------- band mid-UT exp.time magnitude Rc June 12 11:23 4 x 1 min. > 16.7 mag (upper limit) Ic June 12 11:34 4 x 1 min. 17.1 mag +/- 0.3 mag ---------------------------------------------------------------