It has always been ESO's aim to operate the VLT in an interferometric mode (VLTI) which allows the coherent combination of stellar light beams col lected by the four 8-m telescopes and by several smaller auxiliary telescopes. In December 1993, in response to financial difficulties, the ESO Council de cided to postpone implement at ion of the VLTI, Coude trains and associated adaptive optics for all the UTs but included provisions for continuing tech nological and development programmes devoted to the aim of reintroducing these capabilities at the earliest possible date. The desirability of carrying out the full VLTI programme as originally envisaged at the earliest possible moment has not, however, diminished, es pecially in view of VLTI's exceptional capabilities and resulting potential for new and exciting discoveries. In recent years, interferometric projects have begun to playa central role in ground-based high-resolution astronomy, and numerous instruments have been completed or are in the process of construc tion. Several large-aperture interferometers will probably co me on-line near the turn of the century. The impending presence of these new instruments represents an important incentive both for clarifying the scientific cases for various VLTI implementation plans and for ensuring VLTI's competitiveness in the international context over the next 1O~20 years.
Table of Contents1. Interferometry Tutorials (All You Wanted to Know About Interferometry But Were Afraid to Ask).- to Interferometry.- An Introduction to Interferometry with the ESO Very Large Telescope.- Interferometry in Practice.- Astrometry with O/IR Interferometers.- 2. Solar System, Extrasolar Planets, Low Mass Stars and Brown Dwarfs.- Solar-System Observations with the VLTI.- Giant Planet Formation and the Masses of Extrasolar Planets.- Theory of Very Low Mass Stars, Brown Dwarfs and Extra-Solar Giant Planets.- On the Detection of Exo-Zodiacal Light by Nulling Interferometry with the Magellan Telescopes.- Direct Observation of Extrasolar Planets with an Infrared Interferometer.- 3. Agn and Starburst Galaxies.- VLTI Observations of Radio-Loud Active Galaxies.- Observations of Extragalactic Sources Near Bright Stars.- AGN Models and Fringe Visibilities.- AGNs at VLTI Scales.- The AGN Dance: Astrometric Variability as the Result of Supernova Explosions in Nuclear Starbursts.- Adaptive Optics Observations of Starburst Galaxies.- Cosmology with the Very Large Telescope Interferometer: Using a Space-Based Astrometric Reference Frame.- 4. The Potential of VLTI and the Connection with Related Techniques.- Tailoring an Interferometer to Its Science and Vice Versa.- Some Aspects of the VLTI’s Potential for Binary Star Research.- Combining Mid-Infrared Lunar Occultations and VLTI Measurements.- 5. Hot Stars.- Interferometric Observations of Be Stars.- Spectroscopic and Photometric Support for Interferometric Observations of Be Stars.- Imaging of Wolf-Rayet Stars with the VLTI.- 6. Circumstellar Environments and Mass Loss.- AGB and Post-AGB Stars: An Overview.- Winds of Red Giants and Supergiants: Basic Physical Processes, Structure and Appearance.- Study of Late-Type Stars with the Infrared Spatial Interferometer of the University of California at Berkeley.- Interferometric Studies of Late Phases of Stellar Evolution.- Interferometric Imaging of Late-Type Stars with the VLTI.- Geometry of Post-AGB Shells.- New Insights in Close Circumstellar Physics Using Interferometry.- 7. Star Formation and Early Stellar Evolution.- Circumstellar Disks in the Early Phases of Star Formation.- Outflows from Young Stars.- Disks Around Young Stars.- 8. Stellar Populations and Galactic Center.- Observing the Galactic Center with the VLTI.- The VLTI and the Galactic Center He I Cluster.- Globular Cluster Proper Motions.- 9. Stellar Diameters and Surface Structure.- Indirect Imaging of Stellar Surface Structure.- Stellar Surface Observations with the VLTI.- On the Scale of Photospheric Convection.- Observing Stellar Surfaces with a High-Precision Infrared Interferometer.- Studying the Coolest Giant Stars at Milliarcsecond Resolution.- The Temperature Scale of the M Dwarfs.- Observations of Cepheids with the VLTI.- Conference Summary.- The VLTI and the Universe: Conference Summary.- Poster Papers.- Simulations of VLTI/VISA Imaging Observations of Young Stellar Objects at 2.2?m.- Speckle Observations of Post-Hipparcos Late-Type Double Stars.- Wavefront Characterization for High Angular Resolution Techniques.- Interfero Coronography at O.C.A..- Simulation of Speckle Images for a Field Wider Than the Isoplanatism Angle.- Visibility Losses Due to Atmospherical Spectral Decorrelation in Michelson Interferometry.- High-Resolution Measurements of Close Binary Stars and the Probability Imaging Technique.- Late-Type Stars at High Angular Resolution: Observations and Modelling.- Interferometric Observations of Mira Stars.- Results of Studies on the Environmental Factors Affecting the VLTI Performance.- Internal Optical Path Calibration System for VLTI.- Pupil Mask Interferometry of M8E-IR.- Observations of the Close Binary System ? Lyrae with the GI2T Interferometer.- Stellar Winds of T Tauri Stars.- Operating the VLTI in the Thermal Infrared.- Multi-speckle Interferometric Imaging with the VLTI and the LBT at Optical Wavelengths.- Infrared Interferometric Imaging with the VLTI in the Multi-speckle Mode with a Combination of the 8 m UTs and the 2 m ATs.- Thermal IR Imaging with MAX: Pushing the Limit of Single-Dish Ground-Based Observations.- Differential Interferometry and the Non-axisymmetric Envelope of ? Cas.- HST Imaging of GM Aurigae: A Circumstellar Disk Seen in Scattered Light.- Software Concept for Four-Dimensional Bispectral Analysis of Stellar Interferograms.- Real-Time Image Compression Method for Astronomical Interferograms.- Synthetic Images from Dynamic Model Atmospheres of C-Rich Long-Period Variables.- Brightness Profiles and Spatial Spectra of Dynamical Models for C-Rich Circumstellar Dust Shells Around Long-Period Variables.- Author Index.