1. Department of Physical Sciences, University of Napoli Federico II, via Cinthia 9, I-80126 Napoli, Italy
2. INAF - Astronomical Observatory of Capodimonte, via Moiariello 16, I-80131 Napoli, Italy
3. INFN section of Naples, via Cinthia 6, I-80126, Napoli, Italy
4. DIETI, University of Naples Federico II, Via Claudio, 21, I-80125 Napoli, Italy
5. Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, the Netherlands
6. National Centre for Nuclear Research, Astrophysics Division, PO Box 447, PL-90-950 Łódź, Poland
7. Kapteyn Astronomical Institute, University of Groningen, PO Box 800, NL-9700 AV Groningen, the Netherlands
8. INAF - Osservatorio Astronomico di Padova, via dell’Osservatorio 5, I-35122 Padova, Italy