Astrometry encompasses all that is necessary to measure the positions and motions of celestial bodies: observational techniques, instrumentation, processing and analysis of observational data, and reference systems and frames, as well as the resulting astronomical phenomena. It is fundamental to all other fields of astronomy, from the focusing of telescopes to navigation and guidance systems and distance and motion determinations for astrophysics. Starting from basic principles, this work provides the principles of astrometry at milli- and micro-arcsecond accuracies and will be an invaluable...

On the occasion ofthe second edition ofthe book, it appeared necessary to up- date information that was already seven years old. Astrometry has recorded tremendous advances during these last years, so that, in addition to cor- recting identified errors and misprints, there are many major modifications. Among the events that forced me to modify significantly the contents of the book, the most important are the release of the Hipparcos and Tycho cata- logues, the introduction of CCD astrometry, the decision of the International Astronomical Union to adopt a new celestial reference frame, the...

The driving idea, in organizing this Symposium on "Relativity in Celestial Mechanics . and Astrometry" was that, in recent years, the ac- curacy of several Astrometric techniques has so much increased that re- lativistic effects are no more marginally mentioned in academic presen- tations but have become an intrinsic part of the interpretation of all the positional data. Techniques such as V. L. B. I. , space probes, lunar lasers, etc ...have greatly contributed to reduce the accuracy level to an angular equivalent of a few milliarc-seconds. HIPPARCOS will extend this trend to stellar...

This book on reference systems is the first comprehensive review of the problem of celestial and terrestrial reference systems and frames. Over 20 years, the importance of this problem emerged slowly as the accuracy of new observational techniques improved. The topic has already been approached in several symposia such as Stresa (1967), Morioka (1971), Perth (1973), Columbus (1975, 1978 and 1985), Kiev (1977) and San Fernando (1978). Two IAU colloquia held in Turin (1974) and in Warsaw (1980) were exclusively devoted to discuss reference systems. During this time, the problem of terrestrial...

After the launching of the first artificial satellites preceding interplanetary vehicles, celestial mechanics is no longer a science of interest confined to a small group of astronomers and mathematicians; it becomes a special engineering technique. I have tried to set this book in this new perspective, by severely limiting the choice of examples from classical celestial mechanics and by retaining only those useful in calculating the trajectory of a body in space. The main chapter in this book is the fifth, where a detailed solution is given of the problem of motion of an artificial satellite...