R. Samadi (1,2), F. Kupka (3), M.J. Goupil (1), Y. Lebreton (4), C. van't Veer-Menneret (4) ((1) Observatoire de Paris, LESIA, CNRS UMR 8109, Meudon, France, (2) Observatorio Astronomico UC, Coimbra, Portugal, (3) Max-Planck-Institute for Astrophysics, Garching, (4) Observatoire de Paris, GEPI, CNRS UMR 8111, Meudon, France)