Celestial fundamental catalogues are a prerequisite for the determination of absolute positions and motions in space. Presently, positional astrometry is at the watershed between classical fundamental catalogues, based on moving reference stars, and modern catalogues, based on extragalactic reference objects with non-measurable motion. This book addresses the concepts and methods of the respective construction techniques leading to the stellar frame of the FK5 (fifth fundamental catalogue) and to the newly adopted extragalactic radio reference frame, ICRF (international celestial reference frame), with its extension to optical wavelengths by the Hipparcos Catalogue. While principal outlines of meridian circle observations are given, emphasis is put in some detail on the VLBI technique as applied to astrometry, and to the observational techniques used in the Hipparcos mission, including the tie of the originally non-anchored rigid Hipparcos sphere into the ICRF.
"Such a book was desired since long time and the present compact and, on the other side, very detailed and competent description, analysis and explanation of the basic part of astrometry fills a gap in the scientific literature and fulfils the needs of a variety of disciplines from geodesy up to fundamental physics. [...] One of the many advantages of this book is the fact that it is readable for and well understood by nonexperts in the field." (Journal of Geodesy, 2001)
"The time is propitious for this scholarly book. You can find in it the details of how this leap forward in positional astronomy was achieved and marvel at it." (The Observatory, 2001)
"I can only cite what Viktor Abalakin says in the Prologue: The book, revealing the fundamentals and principles of the art of Fundamental Catalogue construction on the basis of processing optical observations of stars and radio measurements of extragalactic sources, is a timely manual of long-lasting value for everybody who is practically engaged in the field of Astrometry." (Astronomische Nachrichten, 2002)
"The most attractive aspect of Walter and Sober's book is the attempt of erecting a bridge between the traditional optical astrometry and the newborn radio astrometry. The book is addressed mainly to the Astrometric public in general. It is composed of two complementary parts dedicated to a detailed description of both observation methods, and the techniques employed in the compilation of the so-called fundamental reference systems [...] For an Astrometry expert, the book could be separated in two volumes, his attention being raised by the complementary part. The actual unified release, however, has certainly a place in any Astronomy bookshelf, even in an amateur's one, as a rich reference source on all questions concerning reference frames and systems." (Celestial Mechanics and Dynamical Astrometry, 2003)