1. I. Physikalisches Insitut, Universität zu Köln , Zülpicher Strasse 77, D-50937 Köln, Germany
2. Center for Data and Simulation Science, Universtät zu Köln , Albertus-Magnus-Platz, D-50923 Köln, Germany
3. Astronomical Institute, Academy of Sciences of the Czech Republic , Bocni II 1401, CZ-14131 Prague, Czech Republic
4. Astronomical Institute, Faculty of Mathematics and Physics, Charles University , V Holešovičkách 2, CZ-18000 Praha 8, Czech Republic