The radial distribution of the two stellar populations in NGC 1851 A. P. Milone, P. B. Stetson, G. Piotto, L. R. Bedin, J. Anderson, S. Cassisi and M. Salaris A&A, 503 3 (2009) 755-764 Published online: 15 June 2009 DOI: 10.1051/0004-6361/200912256