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Astronomical Almanac
Direct answer
Astronomical Almanac: The Astronomical Almanac is an annual technical reference containing authoritative astronomical and geodetic data for use by observatories, navigators, surveyors, scientists, and software developers.
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At a glance
- Found in
- Historical Almanacs & Instruments
- Related
- Almanac, Nautical Almanac, Astrolabe, Armillary Sphere
The Astronomical Almanac is an annual authoritative reference for precise astronomical data.
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The story behind Astronomical Almanac
National observatories developed annual ephemerides for navigation and astronomy; the current publication continues a long collaboration between the U.S. and U.K. nautical almanac offices.
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The Book of the Sky
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Why Astronomical Almanac matters
Astronomical Almanac supplies documented positions, time scales, constants, and phenomena that allow independent calculations to share a common reference system.
How to read Astronomical Almanac
the Astronomical Almanac or its official data services speaks to precision work, citing the edition, table, time scale, coordinate frame, and any interpolation.
Astronomical Almanac in practice: an example
A researcher may consult the almanac for apparent positions, Earth-orientation quantities, or definitions used in an observing calculation.
Where readings of Astronomical Almanac go wrong
The usual misreading is to copy a value without its units, epoch, reference frame, and time scale or assume an older edition represents current standards.
Sources and editorial method
Research references used for this entry include:
- U.S. Naval Observatory: Astronomical and Navigational Almanacs - Official description of current Astronomical Almanac and Nautical Almanac publications.
- U.S. Naval Observatory: Astronomical Almanac Glossary - Reference definitions for astronomical coordinates, events, calendars, and time scales.
- Source
- The Great Almanac Dictionary
- Category
- Historical Almanacs & Instruments
- Last updated
- 2026-09-26
Consult official astronomical tables
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Common questions
What is the Astronomical Almanac?
The Astronomical Almanac is an annual technical reference containing authoritative astronomical and geodetic data for use by observatories, navigators, surveyors, scientists, and software developers.
What do people get wrong about the Astronomical Almanac?
The usual misreading is to copy a value without its units, epoch, reference frame, and time scale or assume an older edition represents current standards.
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