The United Kingdom Hydrographic Office

The Astronomical Almanac, The Nautical Almanac, The Star Almanac, UK Air Almanac, Astronomical Phenomena, NavPac & Compact Data, Planetary & Lunar Coordinates

HMNAO's astro-navigation software package, links for information, registration and updates.

Explanatory Supplement to The Astronomical Almanac, NAO Technical Notes & Astronomical Information Sheets

Websurf, Eclipses Online, Crescent Moon Watch, The Astronomical Almanac Online, Sun, Moon, Rise/Sets, Calendarial, Observatories and many other astronomical data services.

Rapid Sight Reduction Tables (AP3270), Sight Reduction Tables for Marine Navigation, and various Sight Reduction forms for download.

Information required concerning the Copyright and Licensing of HMNAO products and services.