Institution: | (1) Geodetic Institute of the University of Bonn, Nussallee 17, D-53115 Bonn, FRG;(2) Shanghai Observatory, 80, Nandan Road, 200030 Shanghai, P.R. of China;(3) Hartebeesthoek Radio Astronomy Observatory, PO Box 443, 1740 Krugersdorp, South Africa;(4) Istituto di Radioastronomia, Via Irnerio 46, I-40126 Bologna, Italy |