Foreword

The 5th biennial symposium of the European VLBI Network, entitled EVN-2000 was organised by the VLBI group at Onsala Space Observatory. Meetings were held at the observatory and its parent University, Chalmers University of Technology, in Göteborg from June 29 - July 1, 2000. More than 80 astronomers attended the symposium, including many research students and new users of the Network; 15 different countries were represented. Many young participants were supported through the European Union's Framework and Access programmes. Onsala is the longest standing VLBI observatory in Europe, having performed the first transatlantic VLBI observations in 1968 and having a long record of VLBI measurements both in Astronomy and Geodesy. It was appropriate, therefore, that the symposium took place in its 50th year of operation.

The last EVN symposium saw the opening of the new EVN Correlator Centre at JIVE, in Dwingeloo, the Netherlands. This symposium contains reports on data processed with the new correlator, a new milestone for European VLBI. Another important milestone was also represented - Space VLBI or VLBI between the ground arrays and an antenna in space. The Japanese HALCA satellite-borne antenna has been operating with the EVN and global VLBI arrays at wavelengths of 6 and 18 cm and some of the results of those observations are presented here.

The range and variety of problems tackled by the VLBI technique are ever growing and today they encompass many branches of astrophysics and astronomy. Topics include AGN continuum observations with ever higher resolution via millimetre-wave and Space VLBI. Weak sources can now be imaged using the phase-referencing technique and whole new classes of astronomical object are now being regularly imaged for the first time at milli-arcsecond resolution. Targets include nearby radio stars and associated searches for low mass companions via astrometry; and evolving supernovae in external galaxies. Impressive movies of these evolving supernovae have been made. Also reported in these pages is deep imaging of the weak extragalactic radio source population in the Hubble Deep Field. These observations are beginning to probe the microjansky source population at milli-arcsecond resolution; and turning up examples of compact high-z starburst galaxies.

Spectral line measurements are on the increase and again address a fascinating variety of questions from star formation to accretion discs around black holes. This work is made possible by the presence of compact cosmic masers which can be used as tracers of dynamics. Exciting new results in Galactic astronomy concern rotating discs around putative protostars and the evolution of shells of SiO masers around pulsating Mira variables and infrared stars. In the extragalactic field water maser observations are giving more evidence for accretion discs around ten million solar mass black holes in Seyfert galaxies while measurements of red-shifted atomic hydrogen have revealed the atomic component of tori around AGN.

Closer to home VLBI is also used extensively in the service of geodesy. Geodetic VLBI provides unique information about Earth orientation and rotation and provides a high accuracy check on other geodetic techniques.

An atmosphere of friendliness and collaboration surrounded the conference as VLBI friends from the observatories at the different ends of the baselines mingled with the user community, some of whom have never been to a radio observatory. User-friendliness is important to the EVN - this meeting showed that we are well on the way to its implementation. Finally, I want to record my thanks to the editorial team who have worked hard to produce these proceedings in good time and also to thank those other people who contributed so much to the smooth running of the meeting - especially Margareta Mattsson, Lars Eriksson and Vivian Svensson.

Roy Booth

Director, Onsala Space Observatory, Sweden