Institution: | Argelander Institute for Astronomy, University of Bonn, Auf dem Huegel, D-53121 Bonn, Germany;Institute of Astrophysics &Geophysics, University of Liège, 17 avenue du 6 Août, B-4000 Liège, Belgium;Department of Physics &Astronomy, The University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH;National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012, P. R. China |