Aristotle University of Thessaloniki, Department of Physics, Section of Astrophysics, Astronomy and Mechanics, Thessaloniki, 54124 Greece; National Observatory of Athens, Institute for Space Applications and Remote Sensing, Penteli, Athens, 152 36 Greece
National Observatory of Athens, Institute for Space Applications and Remote Sensing, Penteli, Athens, 152 36 Greece
Centre d'Étude des Environnements Terrestre et Planetaires, CNRS-Observatoire de Saint-Maur, 4, avenue de Neptune, Paris, 94107 France