TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2412 SUBJECT: XRF 030723: Subaru Optical Observations DATE: 03/10/08 02:31:38 GMT FROM: Nobuyuki Kawai at Tokyo Tech N. Kawai, G. Kosugi, Y. Komiyama, H. Furusawa, Y. Urata, and T. Yamada on behalf of the Subaru GRB team report: "We have observed the field of XRF030723 (=H2777, GCN 2320) with the Subaru Prime Focus Camera on 2003 September 29 - October 3 UT in V, Rc, Ic, and z' bands. We detected an unresolved source at the position of the proposed host galaxy (Fynbo et al. GCN 2403) in Rc, Ic and z' bands. With the preliminary analysis, the magnitude of the source was R=27.6 +/- 0.4 (2.4 hour exposure, mean seeing 0.7 arcsec). It has a red color, and we were not able to obtain significant detection of the source with the 1.7 hour exposure in V band. The images are posted at http://www.naoj.org/staff/george/Distribute/XRF030723/XRF030723.html."