Astrometry for Astrophysics: Methods, Models, and ApplicationsThe field of astrometry, the precise measurement of the positions, distances and motions of astronomical objects, has been revolutionized in recent years. As we enter the high precision era, it will play an increasingly important role in all areas of astronomy, astrophysics and cosmology. This edited text starts by looking at the opportunities and challenges facing astrometry in the twenty first century, from space and ground. The new formalisms of