Isopistonic angle for multi-aperture interferometers from isoplanatic angle T. Elhalkouj, A. Ziad, R. G. Petrov, M. Lazrek, Y. Elazhari and Z. Benkhaldoun A&A, 477 1 (2008) 337-344 Published online: 26 October 2007 DOI: 10.1051/0004-6361:20078173