The Explanatory Supplement to the Astronomical Almanac offers explanatory material, supplemental information and detailed descriptions of the computational models and algorithms used to produce The Astronomical Almanac, which is an annual publication prepared jointly by the US Naval Observatory and Her Majesty's Nautical Almanac Office in the UK. Like The Astronomical Almanac, The Explanatory Supplement provides detailed coverage of modern positional astronomy. Chapters are devoted to the celestial and terrestrial reference frames, orbital ephemerides, precession, nutation, Earth rotation, and coordinate transformations. These topics have undergone substantial revisions since the last edition was published. Astronomical positions are intertwined with timescales and relativity in The Astronomical Almanac, so related chapters are provided in The Explanatory Supplement. The Astronomical Almanac also includes information on lunar and solar eclipses, physical ephemerides of solar system bodies, and calendars, so The Explanatory Supplement expounds upon each of these topics as well. The book is written at a technical, but non-expert level. As such, it provides an important reference for a full range of users including astronomers, engineers, navigators, surveyors, space scientists, and educators.
- Introduction to Positional Astronomy
- Relativity for Astrometry, Celestial Mechanics and Metrology
- The Fundamental Celestial Reference System
- Terrestrial Coordinates and the Rotation of the Earth
- Precession, Nutation, and Earth Rotation
- Orbital Ephemerides of the Sun, Moon, and the Planets
- Planetary Satellites and Rings
- Physical Ephemerides
- Eclipses of the Sun and Moon
- Astronomical Phenomena
- Stars and Stellar Systems
- Computational Techniques
- Bases and Constants
Sean E. Urban is Chief of the Nautical Almanac Office of the US Naval Observatory and a member of the American Astronomical Society, the Division of Dynamical Astronomy, and the International Astronomical Union's Division I (Fundamental Astronomy), Commission 4 (Ephemerides), and Commission 8 (Astrometry). In 1985, he was hired as a staff astronomer in the Astrometry Department of the US Naval Observatory, where he eventually rose to Chief of the Cataloging and Requirements Division. He has authored or co-authored over 70 articles, most on positional astronomy.
P. Kenneth Seidelmann is a Research Professor at the University of Virginia, USA and previously held the post of director of Astronomy at the US Naval Observatory. His recent work has focused on space astrometry missions, Origins Billion Star Survey (OBSS), Astrometric Mapping Explorer (AMEX), and the Full-sky Astrometric Mapping Explorer (FAME). He is Chair of the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements and the Celestial Mechanics Institute.