Optical behavior of GRB 061121 around its X-Ray shallow decay phase T. Uehara, M. Uemura, A. Arai, R. Yamazaki, K. S. Kawabata, M. Ohno, Y. Fukazawa, T. Ohsugi, M. Yoshida, S. Sato and M. Kino A&A, 526 (2011) A92 Published online: 04 January 2011 DOI: 10.1051/0004-6361/201015911