Astronomical and Navigational Almanacs
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Picture of almanacs Scientific research, timekeeping, calendars, and navigation have all depended upon the practical skills of positional astronomy for thousands of years. Today, in the United States, the U.S. Naval Observatory produces the data for celestial navigation and positional astronomy on behalf of the nation.

As part of this responsibility, and in a long-standing collaboration with Her Majesty's Nautical Almanac Office in the United Kingdom, the Nautical Almanac Office at the U.S. Naval Observatory produces several annual almanacs. Each edition contains data for one year and is published six months or more in advance of the edition year. Her Majesty's Nautical Almanac Office maintains the copyright on the material it contributes.