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HMNAO's Astronomical Data Portal

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HMNAO logo

A wealth of astronomical information produced by HMNAO. These data include daily rise and set times for 106 locations around the British Isles, UK maps with monthly isochrones of sunrise and sunset, definitions of twilights, transits of Venus between the 11th and 27th centuries, Daylight & Moonlight Diagrams and Observatory Data for observatories around the world. Other information includes personal histories by D.H. Sadler, Superintendent 1936-1972, and G.A. Wilkins, Superintendent 1972-1989. News items are also available.

Websurf logo

HMNAO's Websurf provides a range of astronomical information in both pre-calculated and dynamic forms. The dynamical information covers rise/set times, azimuth and altitudes, Islamic prayer times, first sighting of new crescent Moon, Moon phases, equinoxes and solstices and an Almanac giving solar, lunar and planetary data for a specific location and time. Our Info option provides access to Astronomical & Calendarial Sheets, transits of Venus, and the Time Zone map.

Eclipses Online logo

HMNAO's canon of eclipses contains a wealth of information on solar and lunar eclipses from 1501 CE to 2100 CE. It is based on software used in the production of The Astronomical Almanac and provided in conjunction with the US Naval Observatory. This canon of 1421 solar and 1460 lunar eclipses provides global and local circumstances, animations and eclipse panoramas for partial, annular, total and hybrid solar eclipses. Most of the information can be downloaded.

Crescent Moon Watch logo

Participate in HMNAO's Crescent Moon Watch project. Predicting the first sighting of the new crescent moon has been attempted since the time of the Babylonians and perhaps earlier still. Studies published by Schaefer and Doggett of Moon Watch programs in the 1980's and 1990's have been used in a method of predicting the new crescent moon developed by Yallop, a former Superintendent of HMNAO.

AsA Online logo

The Astronomical Almanac Online, the companion to the USNO & HMNAO's premier work The Astronomical Almanac.

Charges and Conditions of Supply of Information for Legal Purposes

Astronomical information that is required for legal purposes such as the positions and times of rising and setting of the Sun and Moon and the times of the Hours of Darkness may be supplied in appropriate circumstances in the form of a Section 9 Statement of Witness (Criminal Justice Act, 1967, s.9; Magistrates' Courts Act 1980, ss.5A(3)(a) and 5B; Criminal Procedure Rules 2010, Rule 27.1). Given sufficient warning, these statements will be provided for a fee of £80.00+VAT. If the statement is required in less than 5 working days from the date of the submission of the original request, a fee of £120.00+VAT will be charged, rising to £160.00+VAT where less than 2 days notice is given. In those cases where more complex information is required, the work will be charged at a rate of £80.00+VAT per hour.

The times are given in the 24-hour clock system and are in GMT/BST for the United Kingdom; the use of any other standard-time system must be specified in advance. The geographical co-ordinates of named towns will be taken from The Times Atlas or the Ordnance Survey Gazetteer unless the requester gives a preferred set of coordinates e.g. ordnance survey coordinates, a post code or latitude and longitude. In other cases, on the UK mainland, co-ordinates will be taken from cross-checked sources of online mapping software.

All requests for information should normally be made in writing (by post, fax or e-mail). An estimate of the charge will be sent if necessary. A copy of the conditions of supply of information will be sent to the requester. Once an acceptance of the conditions has been received by this office, the statement will be dispatched. An invoice will be sent under separate cover giving details of the method of payment.

The UK Hydrographic Office does not accept any responsibility for any loss or damage arising from the use of data supplied or of any information contained in any communication about the data.

Every endeavour will be made to meet requests for the supply of astronomical data required for publication and other purposes as promptly as possible, but the right is reserved to decline to do so without giving reasons, or to defer the production if necessary to the priorities of HM Nautical Almanac Office or the UK Hydrographic Office.

Weather Information

Please note that HMNAO cannot provide legal statements concerning weather conditions. The Meteorological Office, should be consulted if legal reports or expert witness testimony on prevailing weather conditions are required.

Visibility of the New Crescent Moon

HMNAO produces information sheets which give the date of earliest visibility of the new crescent Moon for each lunar month for a selection of cities in the UK and around the world for an interval of 5 years. In addition, there are information sheets which give the local date, local mean time and place of the earliest sighting of the new Moon for the same interval.

WebSurf: MoonViz Output thumbnail By using the "Moonviz" option of Websurf, visibility predictions for the new crescent Moon can be generated for any location on the Earth and for any range of months. Here is an example of the output for London for January 2011.

Crescent Moon Watch logo

Take part in HMNAO's Crescent Moon Watch project by observing the new crescent Moon and recording your observations.

Prayer Times

Websurf: Prayers Output thumbnail By using the "Prayers" option of Websurf, the seven daily Muslim prayer times for any location on Earth and for any range of dates can be calculated. The prayer times can be optimised to particular astronomical phenomena by the user. Here is sample output for London for the first week of January 2011.

Astronomical and Calendarial Data

Astronomical Information Sheet thumbnail

HM Nautical Almanac Office produces specially-prepared annual calendarial sheets containing general astronomical information including seasons (solstices and equinoxes), phases of the Moon, eclipses of the Sun and Moon, the start and end of UK summer time (BST), principal data on civil and religious calendars and bank holidays (see below) in the United Kingdom. Please note that all times are quoted in Greenwich Mean Time.

Data are generally available several years in advance, and may be reproduced in diaries, calendars, newspapers, almanacs and other publications subject to copyright & licensing by the UK Hydrographic Office. Commercial use of these data requires a licence from the UK Hydrographic Office and will incur a supply charge of £25.00+VAT (where appropriate).

The following links give information concerning news about updates and calendarial issues.

The following Astronomical and Calendarial sheets are available for purchase:

  • 2012 - AIS No. 96; Created 2006 November / Updated 2011 March
  • 2013 - AIS No. 97; Created 2008 May / Updated 2011 December
  • 2014 - AIS No. 98; Created 2008 December
  • 2015 - AIS No. 99; Created 2009 December
  • 2016 - AIS No. 100; Created 2010 July
  • 2017 - AIS No. 104; Created 2011 December
  • 2018 - AIS No. 105; Created 2012 December
Data Sheets issued and available for downloading for personal use only ... 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
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Summer Time & Bank Holidays

The latest information on UK Bank holidays and any changes to Summer Time arrangements can be found at the following UK Government web sites:

Potential Customers

Here are some examples of the date we calculate.

  • Standard Computed Data

    The following types of data can be produced by HM Nautical Almanac Office for any specified place for each day of a calendar year:

    • Times and azimuths of sunrise and sunset;
    • The Hours of Darkness (formerly known as "lighting-up times");
    • Times of the start and end of Civil, Nautical or Astronomical Twilight;
    • Times and azimuths of moonrise and moonset;
    • First visibility of the new crescent Moon;
    • Muslim prayer times;

    The supply charge for one type of computed data for a single place for one calendar year is £40.00+VAT. Additional types of data / places / years are charged at the rate of £8.00+VAT per set if ordered at the same time. These data may require a licence from the UK Hydrographic Office.

  • Legal Statements

    We provide Statements of Witness in criminal and civil trials in which astronomical factors such as the time of sunset or twilight or the position of the Sun in the sky play an important role.

  • Muslim Community Crescent Moon Watch logo

    The Muslim community worldwide regulates its daily prayers by the position of the Sun, and its calendar by the phases of the Moon. We provide tables of prayer times and predictions of the visibility of the new crescent Moon to Muslims in Britain and around the world. Take part in HMNAO's Crescent Moon Watch project by observing the new crescent Moon and recording your observations.

  • Historians

    Historical events are sometimes linked with the phase of the Moon or the path of an eclipse over the Earth's surface. Our expertise in astronomical calculation enables us to provide definitive information on such phenomena to historians.

  • Newspaper, Diary and Calendar Publishers

    Many diaries and calendars contain information on the phases of the Moon, the seasons and public holidays. National and local newspapers carry daily times of sunrise, sunset, moonrise, moonset and the phase of the Moon. These Astronomical and Calendarial Data Sheets are produced by HMNAO.

  • Astronomers

    HMNAO produces information sheets giving times of sunrise and sunset, astronomical twilight and the amount of moonlight for several major observatories around the world.

  • Outdoor Events

    HMNAO can generate the times of sunset and twilight for organisers of outdoor events and activities including sports, hiking, mountaineering and open-air concerts.

  • Architects and Town Planners

    The shadow cast by a new building is often a crucial factor in deciding the placement of the building in an urban environment. This depends upon the location of the building and the position of the Sun during the course of the year. HMNAO can produce a solar location diagram for a location of your choice.

  • The Armed Services

    Military planners and tacticians need to know the times of sunrise and sunset and strength of moonlight in battlefield situations. HMNAO has provided such information to Britain's armed services at many critical times, from the D-Day landings to the Gulf War.

  • Specially computed data

    HMNAO can provide other types of astronomical information at a charge which depends upon the amount of work involved and whether the information is to be published or to be used commercially. The basic rate for such work is £80.00+VAT per hour, with a minimum charge of £80.00+VAT. Requests for such information should be made directly to HM Nautical Almanac Office.

Information on the relevant copyright and licensing arrangements for the supply of data are available.

Weather and Tidal Information

HMNAO does not provide meteorological data or tidal predictions.
  • For Meteorological data and predictions - please contact The Meteorological Office.
  • For tidal data and predictions - please consult EasyTide at the UK Hydrographic Office.

Daylight & Moonlight Diagrams

Daylight/Moonlight Diagrams: example output thumbnail

These diagrams show Sun rise/set, Moon rise/set, twilights and Moon phases for one calendar month. They are intended to assist astronomers in planning and scheduling observing runs.

Diagrams from 1997 to 2016 are available for the following Observatory sites, ANU - Siding Spring (Australia), Cambridge (United Kingdom), ESO - La Silla (Chile), ING - La Palma (Canary Islands), Mauna Kea - Hawai'i, SAAO - Sutherland (South Africa), and SLR - Herstmonceux (United Kingdom).

Please click the diagram to transfer to the page to make your selection and download the appropriate Adobe Acrobat pdf file.

Data for Observatories

Observers Calendar: example output thumbnail

These pages tabulate Julian dates, sidereal times at 0 hours UT, Sun rise/set times, Moon rise/set times, twilights times and Moon phases for one calendar month.

Calendars for 1997 to 2016 are available for the following Observatory sites, ANU - Siding Spring (Australia), Cambridge (United Kingdom), ESO - La Silla (Chile), ING - La Palma (Canary Islands), Mauna Kea - Hawai'i, SAAO - Sutherland (South Africa), and SLR - Herstmonceux (United Kingdom).

Please click the diagram to transfer to the page to make your selection and download the appropriate Adobe Acrobat pdf file.

World Time Zone Map

HMNAO produces a world time zone map for use in its publications. This version of the map was last updated in September 2014. The pdf version of this map is available for personal use by clicking on the map below.

World Time Zone Map - September 2014

For those wishing to use this map for commercial purposes, please contact for further information. Alternatively, a licence to use the map commercially can be obtained from the UK Hydrographic Office Intellectual Property department.

Frequently Asked Questions

Follow the links to obtain information or data on the following subjects:

Please contact us if you required any further information these or any other related topics.

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