Christian Churches of God -

The Work of



Royal Greenwich Observatory

Editor's note:

The following information was provided by Her Majesty's Nautical Almanac Office (to whom we are indebted for the provision of precise astronomical data) and is current as at June 1997.

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HM Nautical Almanac Office (HMNAO) is a small group of professional experts in the fields of positional and dynamical astronomy and mathematics. HMNAO, although a department of the Royal Greenwich Observatory, is not part of the Particle Physics and Astronomy Research Council’s funded programme and is required to operate on a commercial footing.

HMNAO produces almanacs and astronomical data of all kinds for a wide spectrum of users, including professional and amateur astronomers, navigators, surveyors, the armed services, the legal profession, diary and commercial almanac producers, architects, religious groups, schools, photographers and film units.

There are five annual almanacs, and other publications that appear at longer intervals. The business of almanac production continues to be a joint effort with the Nautical Almanac Office of the United States Naval Observatory. HMNAO also co-operates with other international institutions such as the Jet Propulsion Laboratory and the Bureau des Longitudes.

The contents and fundamental basis of the almanacs are regularly reviewed. Changes are stimulated by resolutions of the International Astronomical Union, the governing body of world astronomy, changes in the requirements of the users, developments in computer hardware and software, and new methods of publishing.

HMNAO undertakes a modest programme of research on the dynamics of planetary satellites including both observational and theoretical work. This leads to improved positions of the satellites which are incorporated into the almanacs and used by astronomers and space scientists worldwide.

The Astronomical Almanac is used in most observatories in the world. It is a reference work that contains the positions of the Sun, Moon, planets and stars to the highest precision, as well as information on eclipses, planetary satellites and other fundamental astronomical data.

The Nautical Almanac is the definitive reference for astro-navigation at sea. It is the most popular of HMNAO’s publications. It can be found on every ship in the Royal Navy, and it is also widely used by commercial shipping and yachtsmen. It is reprinted in Brown’s Nautical Almanac, and is the national almanac of eight other countries. NAVPAC, a comprehensive software package for navigation, available with Compact Data for Navigation and Astronomy 1996 - 2000, is being used by the Royal Navy, and the Royal Navies of Australia and New Zealand.

The RAF have chosen HMNAO to produce the new UK Air Almanac, which is generated automatically using custom-built software written by HMNAO.

All almanac production is designed, wherever possible, to run automatically and all data are thoroughly checked before publication in order to maintain the high standards of the almanacs.

With the advent of the personal computer and the World Wide Web, HMNAO has embarked on electronic publishing. A comprehensive set of web pages is available and work is in progress on a new CD-ROM based almanac.

Requests for astronomical data come in many shapes and forms, ranging from enquiries from the general public concerning the times of sunrise and sunset to tasks requiring specialised knowledge. The latter include requests for Statements of Witness which are used as evidence in court, the production of star maps for the publisher Dorling-Kindersley, and software for the Forestry Commission to calculate the amount of sunlight falling in forest glades.

In August 1999, a total eclipse of the Sun can be seen from South-West England. The booklet A Guide to the 1999 Total Eclipse of the Sun provides definitive information on the eclipse for the whole of the United Kingdom.

The work of HMNAO requires a wide range of skills in areas as diverse as typesetting, computing and graphic design, as well as a thorough understanding of positional astronomy, celestial mechanics, mathematics and numerical analysis. This skill base is uniquely satisfied by the members of HMNAO.

List of Publications

  • The Astronomical Almanac
  • Astronomical Phenomena
  • The Nautical Almanac
  • The UK Air Almanac
  • The Star Almanac for Land Surveyors
  • Compact Data for Navigation and Astronomy
  • Planetary and Lunar Coordinates
  • Sight Reduction for Air Navigation
  • A Guide to the 1999 Total Eclipse of the Sun
  • NAO Technical Notes (series of 71)
  • Astronomical Information Sheets (series of 78)

Contact Information

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