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HM Nautical Almanac Office: Miscellanea

Answers to Frequently Asked Questions

On these pages, you can find information on matters arising from questions received by HM Nautical Almanac Office. Over time, we hope to add more material to these pages.

Currently, we have information on sunrise/set times across the United Kingdom. Maps showing the sunrise/sunset times or the middle of each month are given in addition to specific rise/set times for number of locations across the United Kingdom.

Information on twilights in the United Kingdom can also be found on these pages. This includes definitions of civil, nautical and astronomical twilights and when they occur across the United Kingdom. A table of daily sunrise/set, moonrise/set and twilight times for locations across the British Isles is also provided.

Information is provided on Delta T, the quantity used in relating the time scales used in the generation of planetary ephemerides with the those linked to the rotating Earth.

We have information on the new crescent moons for April and May 2021 corresponding to the start of the Muslim holy month of Ramadan and the start of the Islamic Festival of Eid al-Fitr respectively. We also have information on the new crescent moon for July 2021 corresponding to the month containing the Islamic Festival of Eid-al Adha.

Our current world time zone map is also available on these pages.

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Last modified: Wednesday, 28 April 2021 at 10:07:01 BST