Visiting Scientist
For more details see the research page of the radio astronomy and astroparticle physics group.
I was co-founder and editor of the Galactic Center Newsletter (unitl 2002).
Moreover, you can find (more or less) popular science article on jets (in German, requires some knowledge of astronomy and physics) and on the shadow of the black hole in the Milky Way I have written for "Sterne und Weltraum". A draft of a popular article on LOFAR (in German) is also available, as well as LOFAR article in the German version of Scientific American (July 2008, Spektrum der Wissenschaften).