TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4436 SUBJECT: GRB 060105: Mitsume optical observations DATE: 06/01/05 21:33:51 GMT FROM: Nobuyuki Kawai at Tokyo Tech K. Yanagisawa (OAO/NAOJ), Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the Mitsume collaboration: "We have observed the field of GRB 060105 (Ziaeepour et al. GCN 4429) with the three-color Mitsume 50 cm telescopes at Okayama and Akeno, Japan starting at 9:14 UT (2.4 hours after the burst). The summary of the observations is following: Telescope bands time (UT) exposure --------- ---------- ---------------- ------------ Okayama g', Rc, Ic 09:14 - 09:41 UT 60 s x 20 Akeno V, Rc, Ic 09:32 - 11:20 UT 30 s x 158 --------- ---------- ---------------- ------------ Comparison with the DSS-2R image does not reveal an OT at the position of the XRT error circle. The 10-sigma upper limit magnitudes for the Okayama images are g': 17.1 Rc: 17.3 Ic: 17.5 The images obtained at Okayama can be viewed at http://bragi.oao.nao.ac.jp/support/telescope/grb50/images/GRB060105A.pdf."