1969-1970: Research Fellow of the Belgian Fund for Scientific Research, Liège Institute of Astrophysics, Belgium
1970-1978: Assistant Professor, Liège Institute of Astrophysics, Belgium
1970-1971: Visiting Astronomer, Paris Astronomical Observatory, France
1976: Associated Astronomer, Strasbourg Astronomical Observatory, France
1977-1980: Resident Astronomer, European Space Agency (ESA) International Ultraviolet Explorer (IUE) Ground Observatory, Villafranca del Castillo, Spain
1980-1983: Deputy and Acting Observatory Controller, ESA IUE Ground Observatory, Villafranca del Castillo, Spain
1983-1986: Associated Astronomer, Strasbourg Astronomical Observatory, France
1986-today: Astronomer, Strasbourg Astronomical Observatory, France
1988-1990: Director, Strasbourg Astronomical Observatory, France
1990: Invited Chair Professor, Porto University, Portugal