1. High Energy Astrophysics Laboratory, and MAXI Team, The Institute of Physics and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
2. Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
3. Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8683, Japan
4. The Hakubi Center for Advanced Research, Kyoto University, Kyoto 606-8302, Japan
5. Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto, Kyoto 606-8502, Japan
6. Division of Particle and Astrophysical Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
7. Kobayashi-Masukawa Institute for the Origin of Particles and the Universe, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan