Prepared jointly with Her Majesty's Nautical Almanac Office, United Kingdom Hydrographic Office. Designed in consultation with other astronomers of many countries. Provides current, accurate astronomical data for use in the making and reduction of observations and for general purposes. The Astronomical Almanac Online extends the printed version by providing data best presented in machine-readable form. Online data are provided for several years. Contains data for astronomy, space sciences, geodesy, surveying, navigation, and other applications. Also used for navigation by air and water.The Astronomical Almanac is a joint publication of the U.S. Nautical Almanac Office, United States Naval Observatory (USNO), in the United States and Her Majesty's Nautical Almanac Office (HMNAO), United Kingdom Hydrographic Office (UKHO), in the United Kingdom. This annual publication contains precise ephemerides of the Sun, Moon, planets, and satellites, data for eclipses and other astronomical phenomena for a given year, and serves as a world-wide standard for such information.

The Fifty Year Almanac of Astronomical Events: 2021 to 2070 is a catalog listing a wide range of solar system phenomena as seen from Earth. Each year gives a concise compendium of the most conspicuous and/or significant astronomical events involving the Sun, Moon and the planets. The astronomical events include the following. - solar and lunar eclipses - phases of the Moon - apogees and perigees of the Moon - Equinoxes and Solstices of Earth - aphelion and perihelion (Earth, Mars, Jupiter, Saturn and Uranus) - oppositions and conjunctions of the planets - elongations of Mercury and Venus - close conjunctions of the Moon with the planets and bright stars - close conjunctions of planets with bright stars and other planets - peak of major meteor showers The date and time of each event is given in Greenwich Mean Time (= Coordinated Universal Time). With 200+ events each year, the Fifty Year Almanac includes over 10,200 astronomical events.

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. In the last few decades, new observational techniques have enabled improvements in accuracy by orders of magnitude. Starting from basic principles, this book provides the fundamentals for this new astrometry at milli- and micro-arcsecond accuracies. Topics include: basics of general relativity; co-ordinate systems; vectors, tensors, quaternions, and observational uncertainties; determination and use of the celestial and terrestrial reference systems and frames; applications of new observational techniques; present and future star catalogues and double star astrometry. This comprehensive reference will be invaluable for graduate students and research astronomers.