1. Centre for Astronomy, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, Grudziadzka 5, PL-87-100 Toruń, Poland
2. Janusz Gil Institute of Astronomy, University of Zielona Góra, Prof. Szafrana 2, PL-65-516 Zielona Góra,Poland
3. IESL, Foundation for Research and Technology – Hellas, Voutes, GR-71110 Heraklion, Greece
4. Department of Physics and Institute for Theoretical and Computational Physics, University of Crete, GR-71003 Heraklion Greece
5. Astronomical Institute, St. Petersburg State University, Universitetsky pr. 28, Petrodvoretz, 198504 St. Petersburg, Russia