''The Nautical Almanac'' has been the familiar name for a series of official British
almanacs
An almanac (also spelled ''almanack'' and ''almanach'') is an annual publication listing a set of current information about one or multiple subjects. It includes information like weather forecasts, farmers' planting dates, tide tables, and other ...
published under various titles since the first issue of ''The Nautical Almanac and Astronomical Ephemeris'', for 1767: this was the first
nautical almanac
A nautical almanac is a publication describing the positions of a selection of celestial bodies for the purpose of enabling navigators to use celestial navigation to determine the position of their ship while at sea. The Almanac specifies for ea ...
to contain data dedicated to the convenient determination of longitude at sea. It was originally published from the
Royal Greenwich Observatory in
England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
.
[
]['ESAE 1961': ]
Explanatory Supplement to the Astronomical Ephemeris and the American Ephemeris and Nautical Almanac
' ('prepared jointly by the Nautical Almanac Offices of the United Kingdom and the United States of America', HMSO, London, 1961)['ESAA 1992': ed. P.K. Seidelmann, ]
Explanatory Supplement to the Astronomical Almanac
' (CA, 1992). A detailed account of how the publication was produced in its earliest years has been published by the National Maritime Museum.
Since 1958 (with the issue for the year 1960),
Her Majesty's Nautical Almanac Office and the
US Naval Observatory
United States Naval Observatory (USNO) is a scientific and military facility that produces geopositioning, navigation and timekeeping data for the United States Navy and the United States Department of Defense. Established in 1830 as the Depo ...
have jointly published a unified ''Nautical Almanac'', for use by the navies of both countries.
[
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Publication history
The changing names and contents of related titles in the series are summarised as follows. (The issue years mentioned below are those for which the data in the relevant issue were calculated—and the issues were in practice published in advance of the year for which they were calculated, at different periods of history, anything from 1 to 5 years in advance).
(For many years, official nautical almanacs and astronomical ephemerides in the UK and the USA had a linked history, and they became merged in both titles and contents in 1981.)
In the UK, the official publications have been:
1767–1959
* For 1767–1959, ''The Nautical Almanac and Astronomical Ephemeris'' contained both astro-navigational and general astronomical data (this complete publication was often referred to, for short, especially in the earlier years, as just ''The Nautical Almanac''). From 1832, responsibility for publication was transferred to
Her Majesty's Nautical Almanac Office.
The main distinctive feature of the inaugural issue for 1767 was the tabulation of
lunar distances as a tool to facilitate the determination of longitude at sea from observations of the Moon. Within a few years, the publishers of almanacs of other countries began to adopt the practice of tabulating lunar distances. Lunar distances continued to be published in the UK official almanacs until 1906, by which time their use had declined in practice. For some time thereafter, in the issues for the years 1907–1919, examples of how to calculate them were given instead.
Time: The issues for 1767 to 1833 gave their ephemeris tabulations in terms of Greenwich apparent (not mean) time. This was on the grounds that an important class of user was the 'Mariner', and that 'apparent Time' was "the same which he will obtain by the Altitudes of the Sun or Stars in the Manner hereafter prescribed". Mean time at Greenwich (i.e. mean solar time) was adopted as from the issue for 1834 and continued to 1959. Until the issue for 1924, the time argument for Greenwich Mean Time was counted from 0h starting at Greenwich mean noon (on the civil day with the same number), and starting with the issue for 1925 the commencement point of the time argument was changed so that 0h became midnight at the beginning of the civil day with the relevant number, to coincide for the future with the civil reckoning.
During parts of the period 1767–1959, separate subsidiary titles dedicated to navigation were also published:
* For 1896–1913: Part 1 of the ''Nautical Almanac and Astronomical Ephemeris'' (containing the astro-navigational data) was also published separately as ''The Nautical Almanac & Astronomical Ephemeris, Part 1''.
* For 1914–1951: the former Part 1 (after redesign) was renamed ''The Nautical Almanac Abridged for the Use of Seamen''.
* For 1952–1959: after further redesign, it was again renamed, as ''The Abridged Nautical Almanac'' (and renamed yet again for 1960 onwards as simply ''The Nautical Almanac'').
1960–1980
* From the issues for 1960, the official titles were redesigned and unified (as to content) between the UK and USA, under the titles (in UK) ''The Astronomical Ephemeris'' and (separately) ''The Nautical Almanac''.
Time: A major change introduced with the 1960 issue of ''The Astronomical Ephemeris'' was the use of
ephemeris time in place of mean solar time for the major ephemeris tabulations. But the ''Nautical Almanac'', now continuing as a separate publication addressed largely to navigators, continued to give tabulations based on mean solar time (UT).
1981 to date
* For 1981 to date, the official titles have been unified in UK and USA (as to title as well as (redesigned) content): ''The
Astronomical Almanac
''The Astronomical Almanac''The ''Astronomical Almanac'' for the Year 2015, (United States Naval Observatory/Nautical Almanac Office, 2014) . is an almanac published by the United States Naval Observatory (USNO) and His Majesty's Nautical Almanac ...
'' and ''The Nautical Almanac''.
The British ''Nautical Almanac'' in the United States
In the US, an official (and initially separate) series of
ephemeris
In astronomy and celestial navigation, an ephemeris (pl. ephemerides; ) is a book with tables that gives the trajectory of naturally occurring astronomical objects as well as artificial satellites in the sky, i.e., the position (and possibly vel ...
publications began with the issue for 1855 as ''The
American Ephemeris and Nautical Almanac''; but before that, the British ''Nautical Almanac'' was commonly used on American ships and in the United States – sometimes in the form of an independently printed American 'impression' instead.
[G.W. Blunt White Library at the Mystic Seaport Museum, Mystic, Connecticut, CT 06355, USA, for a copy of an independent 'Second American impression' of (the British title) ''The Nautical Almanac and Astronomical Ephemeris'' for 1804, e.g. at https://library.mysticseaport.org/initiative/ImPage.cfm?PageNum=1&BibId=21382&ChapterId=1 (retrieved Feb 19, 2009)]
Modern alternative data sources
Almanac data is now also available online from the
US Naval Observatory
United States Naval Observatory (USNO) is a scientific and military facility that produces geopositioning, navigation and timekeeping data for the United States Navy and the United States Department of Defense. Established in 1830 as the Depo ...
.
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References
Bibliography
*
Mary Croarken (2002 September). ''Journal of Maritime Research'' (Greenwich: National Maritime Museum).
External links
HM Nautical Almanac Office: PublicationsOnline catalogue to copies of the ''Nautical Almanac'' held as part of the Royal Greenwich Observatory Archives at Cambridge University Library''Nautical Almanac'' on Internet Archive for 1922186118201773etc.
Essay about ''The Nautical Almanac'', by Sophie Waring, with digitised original documents relating to its creation.
{{DEFAULTSORT:Nautical Almanac, The
1767 establishments in Great Britain
British non-fiction books
United States Naval Observatory
Astronomical almanacs