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 in 1992. 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.