C. Itoh, R. Enomoto;, S. Yanagita, T. Yoshida, T. Tanimori, K. Okumura, A. Asahara, G. V. Bicknell, R. W. Clay, P. G. Edwards, S. Gunji, S. Hara, T. Hara, T. Hattori, Shin. Hayashi, Sei. Hayashi, S. Kabuki, F. Kajino, H. Katagiri, A. Kawachi, T. Kifune, H. Kubo, J. Kushida, Y. Matsubara, Y. Mizumoto, M.Mori, H.Moro, H. Muraishi, Y.Muraki, T. Naito, T. Nakase, D. Nishida, K. Nishijima, M. Ohishi, J. R. Patterson, R. J. Protheroe, K. Sakurazawa, D. L. Swaby, F. Tokanai, K. Tsuchiya, H. Tsunoo, T. Uchida, A. Watanabe, S. Watanabe, and T. Yoshikoshi
TeV gamma-rays were recently detected from the nearby normal spiral galaxy NGC 253 (Itoh et al. 2002). Observations to detect the Cherenkov light images initiated by gamma-rays from the direction of NGC 253 were carried out in 2000 and 2001 over a total period of ~150 hours. The orientation of images in gamma-ray-like events is not consistent with emission from a point source, and the emission region corresponds to a size greater than 10 kpc in radius. Here, detailed descriptions of the analysis procedures and techniques are given.