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ADMIRALTY Astronomical Publications

Astronomical information to support marine celestial navigation

Rapid Sight Reduction Tables for Marine (NP303 volumes 1, 2 &3)

​​​Available as a three volume set. Volume 1 is aimed at the navigator using astro-navigation and provides the optimum selection of stars for a three-star fix. Volume 2 covers latitudes between 0° and 40°, with Volume 3 covering latitudes between 39° and 89°.


NavPac and Compact Data (DP330)

​NavPac software enables navigators and astronomers to compute their position at sea. It provides methods for calculating the positions of the Sun, Moon, navigational planets and stars over several years to a consistent precision, with the aid of a pocket calculator, personal computer or laptop.

This publications is used by the Royal Navy and by many navigators who require an independent means of navigation.​​


The Astronomical Almanac (GP100)

A worldwide resource for fundamental astronomical data, the Astronomical Almanac includes contributions from astronomical experts, as well as a wide variety of technical and general astronomical information. This includes:​

  • Positions of the Sun, Moon and planets to milli-arcsecond precision

  • Positions of minor planets and planetary satellites for each year

  • Data relating to Earth orientation, time-scales and coordinate systems

  • Sunrise/set, moonrise/set and twilight times

  • Reference data for stars and stellar systems, observatories and related astronomical constants and techniques.


This is a joint publication with the United States Naval Observatory.


The Star Alamanc (NP321)

The Star Alamanc contains positions of the major and selected bright stars in a tabular format for easy identification. It is ideal for land surveyors who use astronomical observations to determine their geographical position or the direction to true north.


This edition includes:

  • A CD containing the almanac in PDF format and the coefficients representing the positions of the Sun and stars in ASCII files

  • Coefficients for calculating the Greenwich hour angle and declination of all the stars published in The Star Almanac, accurate to about 1 arcsecond

  • Polynomial coefficients for calculating R (GHA Aries - UT), declination, E and semi-diameter of the Sun are also included.


Astronomical Phenomena (GP200)

This publication provides a summary of astronomical events.  It is published several years in advance and contains much of Section A of the corresponding Astronomical Almanac (GP100). 


This publication includes:

  • Phases of the Moon, eclipses of the Sun and Moon

  • Principal occultations, planetary phenomena, elongations and magnitudes of the planets

  • Times of sunrise/set, moonrise/set.

  • Tabulated equations of time, the declination of the Sun and the Greenwich hour angles of the pole stars Polaris and Sigma Octantis