About us

HM Nautical Almanac Office is a small multi-disciplinary group of specialists whose purpose is to provide solutions to astronomical and celestial navigation problems.

We produce astronomical data suitable for a wide range of users, including professional and amateur astronomers, mariners, aviators, surveyors, the armed forces, the police, lawyers, schools and the general public.

Who we are

Founded in 1831, HMNAO was formerly part of the Royal Greenwich Observatory (based in Herstmonceux and then Cambridge).

The UKHO took over the responsibility for HMNAO from April 2006.

Our responsibilities

We produce and provide:

  • almanacs for astronomers, mariners, land surveyors and aviators
  • sight reduction tables for navigation
  • celestial navigation software (NavPac)
  • expert witness testimony for the police and legal profession
  • web services

Web services include:

  • rise/set times of the Sun, Moon and Planet positions and configurations
  • Islamic prayer times
  • moon phases
  • equinoxes and solstices
  • predictions of the first sighting of the new crescent moon
  • eclipses of the Sun and Moon

Our products and services

View details about all our products and how to obtain them..

View details about our services .