BR1202–0725: an extreme multiple merger at z = 4.7 P. Salomé, M. Guélin, D. Downes, P. Cox, S. Guilloteau, A. Omont, R. Gavazzi and R. Neri A&A, 545 (2012) A57 Published online: 07 September 2012 DOI: 10.1051/0004-6361/201219955