Spherical and prcatical astronomy

PREFACE; "The art and science of determining the precise location of a terrestrial point from measurements on natural celestial bodies is the principal subject of this book. Comprehensive treatments of this topic published in English in the past included certain government agency manuals, rather limited in scope, books written mainly for the use of the land surveyor, limited to simple methods of low accuracy, and the practical astronomy books from Chauvenet (1891) to Nassau (1931) which are probably the most comprehensive but for the most part obsolete. Advances in pertinent instrumentation, in computational methods due to the use of computers, and astronomic discoveries and the resolution new concepts and conventions made it necessary to prepare this text. The book is an outgrowth of lecture material presented in courses at the Ohio State University over a period of years. The aim of this book is to bring together an up-to-date balanced selection and treatment of the subject that can serve as an introduction yet is sufficiently detailed to be also used as a teaching text and reference work. A review on the geometric and physical properties of the earth is given in the second chapter. This is followed by three chapters which deal with topics commonly known as spherical astronomy-subjects such as the various celestial coordinate systems and their relation to each other; the variations of star coordinates due to precession, nutation, polar motion, aberration, parallax, refraction, and proper motion; the different time systems including ephemeris and atomic times. The next three chapters describe the various star catalogues and their accuracies, the instrumentation as used in the observatories and in the field, international time coordination and dissemination. The final chapters deal with topics known as 'positional astronomy,' treating first and second order position determination methods. References and numerical examples are included throughout.