1. Dipartimento di Fisica G. Occhialini, Università degli Studi di Milano-Bicocca , Piazza della Scienza 3, I-20126 Milano, Italy
2. INAF - Osservatorio Astronomico di Brera , via Brera 28, I-20121 Milano, Italy
3. INAF - Osservatorio Astronomico di Trieste , via G. B. Tiepolo 11, I-34143 Trieste, Italy
4. Aix Marseille Univ , CNRS, CNES, LAM, F-13013 Marseille, France
5. Department of Physics and Astronomy, University of Alabama in Huntsville , Huntsville, AL 35899, USA
6. National Astronomical Observatory of Japan , 2-21-1, Osawa, Mitaka, Tokyo 181-8588, Japan
7. Subaru Telescope, National Astronomical Observatory of Japan , 650 North A’ohoku Place, Hilo, HI 96720, USA