The VLT Interferometer - ESO

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9.2. OPERATION OF THE VLTI/ADVANCED ARRAY 159 fringe contrast and stability as well as the achievement of routine operation of the VLTI is not part of this phase. One of the most challenging parts of this phase of the VLTI implementation must be the commissioning of the global VLTI control system which will make all interfaces between the subsystems work properly. 9.2 Operation of the VLTI/ Advanced Array At the end of the commissioning, if all components were designed and constructed to meet the specified requirements on eg vibration levels, fringe acquisition in good seeing conditions should be done in a short period of time (few minutes). Interferometers implemented in the last decade with the required quality of engineering, were very successful in that respect. Following the commissioning of the VLTI we expect that for a number of years the operation of the VLTI to consist of a mixture of three observing modes: 1. R&D leading to the improvement of the performance of the VLTI, including fringe contrast optimization, improved systems operation, inclusion of the 8 meter telescopes, optimization of the 8 meter telescopes for interferometry, imaging software development, etc. all aimed at the best possible functioning of the VLTI. 2. Astronomical observing both by interferometry experts and other astronomers using the VLTI in the gradually improving state. 3. Further development of interferometric imaging techniques using the "experimental physics facility" aspect of the VLTI. It might be anticipated that in the beginning of this phase of the VLTI operation the first mode will dominate activities. Gradually the emphasis will have to change to the latter two modes, using routine observing with the array. 9.3 Towards the VLT Interferometer/Extended Array As interferometry with the VLTI matures, as the field of astronomical interferometry develops, and as the goals of the Advanced Array are being realized, it will become clear which aspects of the Extended Array are most needed to make further major progress in high angular resolution imaging. Together with the important astronomical knowledge obtained with the Advanced Array we expect that a powerful case can be made at that time for funding towards
160 CHAPTER 9. OPERATION OF THE VLT INTERFEROMETER this Extended Array. This phase will undoubtedly not occur until after the Advanced Array has achieved routine operation status. 9.4 Remote Observing Remote observing with the VLTI will only be an option in the long term. Because of the highly experimental nature of this rapidly developing part of observational astronomy, it is unrealistic to expect a purely remote observing mode at an early time. "Service Observing" on the other hand would appear to be an early option. 9.5 Other Operational Aspects of the VLTI 9.5.1 Use of 8 meter Telescopes Initially the emphasis for the VLTI will be the use of the auxiliary telescopes for interferometric imaging and the occasional inclusion of the 8 meter telescopes mainly to evaluate and optimize their interferometric performance (eg vibrations). As the VLTI performance is demonstrated by its astronomical results we expect that the user pressure will grow to include the 8 meter telescopes, both because of the resulting higher sensitivities and because of the larger number of baselines achievable. The definition of the VLTI resulting from the present study will allow the switch-over from the use of the auxiliary telescopes to the 8 meter telescopes to occur with a minimum amount of effort. 9.5.2 The Combination of Large and Small Telescopes In chapter 4 it was argued that the use of the 8 meter telescopes for interferometry may be optimal with the use of all 8 meter telescopes at once, rather than one at a time in combination with the auxiliary telescopes. In that way the optimal gain in sensitivity is achieved, a wide field-of-view is still an option, and the diffraction limited angular resolution of the individual telescopes is matched (important in the study of complex objects). On the other hand, in some applications, determined mostly by baseline arguments, it may be desirable to combine the auxiliary telescopes with one or more 8 meter telescopes.
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FOREWORD In November 1988 I propose
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INTRODUCTORY COMMENTS This document
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3.6.2.1 Spectral Dispersion in Imag
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9.4 Remote Observing . . . . . . .
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7.1 Lay-out of the 8 meter telescop
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Chapter 1 Introduction 1.1 General
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1.2. PREMISES AND ASSUMPTIONS 3 and
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8 CHAPTER 1. INTRODUCTION being rou
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Chapter 2 Scientific Aspects of Int
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14 CHAPTER 2. SCIENTIFIC ASPECTS Ta
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2.3. DERIVED DESIRED PROPERTIES FOR
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2.3. DERIVED DESIRED PROPERTIES FOR
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52 CHAPTER 3. OPTO-MECHANICAL ASPEC
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3.2. POLARIZATION EFFECTS IN INTERF
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3.3. FIELD-OF-VIEW EFFECTS IN INTER
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3.6. FRINGE ACQUISITION AND TRACKIN
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76 FRINGE DETECTION CHAPTER 3. OPTO
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3.7. "BLIND FRINGE ACQUISITION AND
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4.1. COMPUTER SIMULATIONS OF MULTIS
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4.2. REDUNDANT VS. NON-REDUNDANT AR
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94 CHAPTER 4. IMAGE FORMATION ASPEC
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96 CHAPTER 4. IMAGE FORMATION ASPEC
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Chapter 5 Adaptive Optics for Inter
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104 CHAPTER 5. ADAPTIVE OPTICS FOR
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106 CHAPTER 5. ADAPTIVE OPTICS FOR
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Page 176 and 177: Bibliography [Afanas'jev et al1988]
Page 178 and 179: BIBLIOGRAPHY [Foy 1988] [Forbes 198
Page 180 and 181: BIBLIOGRAPHY [Reinheimer et al 1988
Page 182 and 183: Chapter 11 Appendices List of Appen
Page 184 and 185: 171 6. encourage the funding and co
Page 186 and 187: 3.2 Koechlin's 12T Results I derive
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The VLT Interferometer - ESO

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