We wish to thank the staffs at the participating observatories for their effort during the observations and the staff at the MPIfR correlator in Bonn. M.J. Rioja also wishes to thank some friends/collaborators for support: Jim Davis for the help on working with SOLVK, Néstor Zarraoa, Antonio Rius and Esther Sardón with OCCAM, and Michael Ratner and José Carlos Guirado with VLBI3. M.J. Rioja is grateful to Richard Porcas for encouragement, valuable comments and discussions on this manuscript. This work was partially supported by the Spanish DGICYT grants PB89-0009 and PB93-0030, the European Union grant CHGECT920011, and the United States National Science Foundation grant AST9303527.
© European Southern Observatory (ESO) 1997
Online publication: May 5, 1998