1. Dipartimento di Fisica e Astronomia ‘G. Galilei’, Università di Padova, vicolo dell’Osservatorio 3, I-35122 Padova, Italy
2. INAF-Osservatorio Astronomico di Padova, vicolo dell’Osservatorio 2, I-35122 Padova, Italy
3. Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, UK
4. Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
5. Département Sciences de la Matière, ENS de Lyon, 46 allée d’Italie, F-69364 Lyon, France
6. Instituto de Astronomia y Ciencias Planetarias, Universidad de Atacama, Copayapu 485, 1530000 Copiapó, Chile