Affiliation: | 1.Department of Astronomy, College of Science, University of Baghdad, 10071, Baghdad, Iraq ;2.Argelander Institut für Astronomie der Universit?t Bonn, Auf dem Hügel 71, Bonn, D-53121, Germany ;3.Helmholtz-Institut für Strahlenund Kernphysik (HISKP), Universit?t Bonn, Nussallee 14-16, Bonn, D-53115, Germany ;4.Charles University in Prague, Faculty of Mathematics and Physics, Astronomical Institute, V Hole?ovi?kách 2, Praha, CZ-18000, Czech Republic ; |