About Us

A brief history of the U.S. Nautical Almanac Office and the Astronomical Applications Department
“An opportunity is now offered to astronomers and men of science in this country, under the patronage of the Navy Department, to promote the cause of sound knowledge and to extend the national usefulness and honor by preparing an ephemeris based upon calculations, which shall be more perfect than those at present employed.”
 CDR Charles Henry Davis, c.1860
These words, written on March 31, 1849 by LT Charles Henry Davis in a letter to Secretary of the Navy William B. Preston, described the prevailing sentiment of the day to establish an American Nautical Almanac.  Although such publications were available from a number of foreign sources, national pride and the belief that American science could produce a more accurate product led to the founding of the Navy’s Nautical Almanac Office in July of that year with LT Davis (pictured at right) as its first Superintendent.
 
Established in Cambridge, MA as a separate entity from the U.S. Naval Observatory, the two offices were linked by mutual needs.  The Almanac Office required the observational skills of USNO’s astronomers, and the Observatory needed the expertise of the mathematicians attached to the Almanac Office.  Harvard astronomer Prof. Joseph Winlock alternated with Davis as Superintendent of the office during this time.
 
The first edition (for the year 1855) of the American Ephemeris and Nautical Almanac was published in 1852 and was tailored to the interests of American mariners, with tables of star positions and solar, lunar, and planetary data computed for the Prime Meridian at Greenwich, England as well as the meridian defined by the Naval Observatory in Washington.
 
When Davis, now a rear admiral, became Superintendent of the U.S. Naval Observatory in 1865, he recommended that the Nautical Almanac Office should relocate to Washington.  The move was completed in 1866.  Although they were still separate entities and maintained separate quarters in Washington, the two institutions were placed under the newly-established Bureau of Navigation, and their work became more intertwined.  A former USNO astronomer, Prof. J.H.C. Coffin, became Superintendent, followed by Prof. Simon Newcomb, who held that office from 1877 until his retirement in 1897.  In 1893, when the Observatory moved to its present location in Georgetown Heights, the Almanac Office moved to the same new location.
 
Administratively, the Office remained separate from the Observatory until 1904, when it became an Observatory Department.
 
In addition to producing the annual almanacs, the new Department began to evolve to produce products for special requirements in the Navy as it began transforming into a projection of American power in the two World Wars of the 20th Century.  A specialized Air Almanac was developed for long-range aircraft navigation, and techniques were developed to track enemy submarines.  As the “Space Age” dawned new requirements for tracking artificial satellites drove the adoption of early computer technology in the production of these specialized products as well as the almanacs.  The Apollo flights to the Moon required an entirely new form of navigation independent of references to the Earth.  The Department provided NASA with specialized navigation charts for all of the Apollo lunar missions.
 
Today’s Astronomical Applications Department was established in 1990.  The Nautical Almanac Office is still an integral part of the Department and still produces almanacs for astronomy, sea, and air navigation.  Since 1911 it has collaborated with Her Majesty’s Nautical Almanac Office in Great Britain in these annual publications.
 
The Department has developed computer software and web-based applications to compute astronomical events and data over a span of 250 years, and provides specialized navigational software for DoD customers.  It also provides customized data to support special operations, and its members conduct fundamental research on the forces that affect the Earth and the space around it.
 
With a heritage stretching back over 170 years, USNO’s Astronomical Applications Department is one of the oldest continuous American scientific endeavors and continues to be a world-renowned authority on astronomical ephemerides and phenomena.
 
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