HST/ACS colour–magnitude diagrams of M 31 globular clusters S. Perina, L. Federici, M. Bellazzini, C. Cacciari, F. Fusi Pecci and S. Galleti A&A, 507 3 (2009) 1375-1392 Published online: 08 October 2009 DOI: 10.1051/0004-6361/200912587