1. Department of Physics and Geology, University of Perugia, 06123 Perugia, Italy
2. LESIA-Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 Place Jules Janssen, 92190 Meudon, France
3. INAF-Astrophysical Observatory of Arcetri, Largo E. Fermi n. 5, 50125 Florence, Italy
4. CNR-IGG Sezione di Firenze, Via Giorgio La Pira 4, 50121 Florence, Italy