Published in Reports on Progress in Physics, Volume 71, Issue 6, pp. 066901 (2008).
astro-ph/0803.2983

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Abstract: Very Long Baseline Interferometry, or VLBI, is the observing technique yielding the highest-resolution images today. Whilst a traditionally large fraction of VLBI observations is concentrating on Active Galactic Nuclei, the number of observations concerned with other astronomical objects such as stars and masers, and with astrometric applications, is significant. In the last decade, much progress has been made in all of these fields. We give a brief introduction into the technique of radio interferometry, focussing on the particularities of VLBI observations, and review recent results which would not have been possible without VLBI observations.

Table of Contents

• INTRODUCTION
• THE THEORY OF INTERFEROMETRY AND APERTURE SYNTHESIS
• Fundamentals
• Sources of error in VLBI observations
• The problem of phase calibration: self-calibration
• Polarization
• Spectral line VLBI
• Pulsar gating
• Wide-field limitations
• VLBI at mm wavelengths
• The future of VLBI: eVLBI, VLBI in space, and the SKA
• VLBI arrays around the world and their capabilities
• ASTROPHYSICAL APPLICATIONS
• Active Galactic Nuclei and their jets
• Stars
• Results from astrometric observations
• CONCLUSIONS
• REFERENCES