1. School of Science and Technology, University of Camerino, Via Madonna delle Carceri, Camerino 62032, Italy
2. Istituto Nazionale di Fisica Nucleare, INFN, Sezione di Perugia, Perugia 06123, Italy
3. IAPS, INAF — Tor Vergata, Roma 00133, Italy
4. SUNY Polytechnic Institute, Utica 13502, NY, USA
5. INAF — Osservatorio Astronomico di Brera, Milano 20121, Italy
6. Al-Farabi University, Al-Farabi, 71, Almaty 050040, Kazakhstan