The book is an introduction to practical astrometry, dealing with the determination of positions, motions, distances and dimensions of celestial bodies ranging from quasars to artificial satellites. The main part is devoted to the description of instruments and observing techniques, and also includes the basic properties of optical instruments and a detailed description of the atmospheric effects on observations. A brief summary of the main phenomena in positional astronomy and of data treatment is given. Although classical astrometric methods are described, emphasis is put on new, more precise techniques such as CCD, optical and radio interferometry, space astrometry, etc. For this 2nd edition, the release of the Hipparcos and Tycho catalogs, the rise in CCD astrometry and the adoption of a new celestial reference frame by the IAU led to a significant modification of the text. And, especially, the outlook for astrometry has been completely rewritten.
