M. Montalto (1), G. Piotto (1), S. Desidera (2), F. De Marchi (1), H.
  Bruntt (3,4), P. B. Stetson (5), A. Arellano Ferro (6), Y. Momany (1,2), R.
  G. Gratton (2), E. Poretti (7), A. Aparicio (8), M. Barbieri (2,9), R. U.
  Claudi (2), G. Grundahl (3), A. Rosenberg (8) ((1) Dipartimento di
  Astronomia, Universit\`a di Padova, Italy, (2) INAF - Osservatorio
  Astronomico di Padova, Italy, (3) Department of Physics and Astronomy,
  Denmark, (4) University of Sydney, School of Physics, Australia, (5) Herzberg
  Institute of Astrophysics, Canada, (6) Instituto de Astronom\'ia, Universidad
  Nacional Auton\'oma de M\'exico, (7) INAF - Osservatorio Astronomico di
  Brera, Italy, (8) Instituto de Astrofisica de Canarias, Canary Islands,
  Spain, (9) Dipartimento di Fisica, Universit\`a di Padova, Italy)