This text details the fundamentals of astrometry at milli- and micro-arcsecond accuracies.Astrometry encompasses all that is necessary to provide the positions and motions of celestial bodies. This includes observational techniques, instrumentation, processing and analysis of observational data, reference systems and frames, and the resulting astronomical phenomena. Astrometry is fundamental to all other fields of astronomy, from the pointing of telescopes, to navigation and guidance systems, to distance and motion determinations for astrophysics. Starting from basic principles, this book provides the fundamentals of astrometry at milli- and micro-arcsecond accuracies. An invaluable reference for graduate students and research astronomers.Astrometry encompasses all that is necessary to provide the positions and motions of celestial bodies. This includes observational techniques, instrumentation, processing and analysis of observational data, reference systems and frames, and the resulting astronomical phenomena. Astrometry is fundamental to all other fields of astronomy, from the pointing of telescopes, to navigation and guidance systems, to distance and motion determinations for astrophysics. Starting from basic principles, this book provides the fundamentals of astrometry at milli- and micro-arcsecond accuracies. An invaluable reference for graduate students and research astronomers.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 invalÔ