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Welcome to HMNAO's Moon Watch web site.
Have you ever wondered at what stage you can see the new crescent moon?

The next new moon will occur on July 16th 2015 at 01:24 GMT/UT or 02:24 BST and the sighting of the new crescent moon signals the end of Ramadan and the start of the Muslim festival of Eid al-Fitr.

The timing of the new moon this month means that a telescopic sighting of the crescent moon may just be possible on July 16th from the south-western tip of South Africa. A sighting of the new crescent moon with the naked eye under excellent conditions may be possible from as far east as southern Brazil and subsequently from most of the rest of South America except the north-eastern part and from the Hawaiian Islands on the same day. Easier sightings of the crescent moon with the naked eye may be possible from French Polynesia and the Cook Islands also on July 16th. Parts of the central band of Asia and southern Europe may be able to make a sighting with the naked eye under excellent conditions on July 17th. Most of the world including southern Asia, the Middle East, Africa and most of the Americas with the exception of Japan, northern Asia, most of northern Europe and Canada will probably make easier sightings with the naked eye on July 17th. The crescent moon should be easily visible worldwide with the possible exception of north-eastern Russia on July 18th which may have to wait until the following day to make its sighting. We would therefore ask observers to make sightings of the crescent moon between July 16th and July 19th and report them to us.

Please note: If you have subscribed to our e-mail warning of the date of the new moon and failed to receive any warning, particularly since November 2009, could you please let us know. A separate computer problem occurred affecting the dispatch of e-mail warnings for May 2012 and June 2012 for which we apologise.

If you go out just after sunset over the three or four days following the instant of new moon and have a look low in the western half of the sky near where the Sun set, you can try and observe the new crescent moon.

You can make the observation with just your eyes or with binoculars or a telescope. Never look at the Sun directly or through binoculars or a telescope as you will damage your eyesight. If you are going to use binoculars or a telescope to find the new crescent moon, you must make sure the Sun has set.

The crescent moon will be faint shortly after new moon but will brighten from night to night as the crescent thickens. Cloud or aircraft vapour trails can easily be mistaken for the Moon so be careful when making the observation.

Scan the western horizon close to where the Sun set. If you can see the Moon, let us know by entering your observation and location in our report form. We need to know the date and time of your observation, what the crescent looked like, where it was in the sky relative to the position on the horizon where the Sun set and something about the weather conditions and you, the observer. Even if the weather is clear and you cannot see the Moon, let us know. A negative observation will also help us!

Come back to this site later in the month and you can find out what you should have seen from your observing site. You can also sign up for an e-mail reminder of the date and time of the next new moon so you can try your observing skills again.

Over time, we will process your observations and try to improve the models we use to predict the first sighting of the new crescent moon. Currently, these predictions produce a classification for a particular date and location ranging from A (crescent easily visible) through to F (crescent impossible to see).

For those groups who use the first sighting of the new crescent moon in their calendars, these predictions are very significant and mark the beginning and end of periods of fasting and festivals. More information on these predictions is available on this site.

This site allows observers to look at the global visibility of the next new moon, to check their observations of the last new moon, to report their observations and to receive/stop e-mail reminders of the next new moon.

Preliminary results will also be reported on the site when they become available.

Further information on the visibility of the new crescent moon for a specific location can be found on our Websurf site by selecting the Moon_Viz option from the menu.
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An ancient Maya calendar
A satellite dish scanning the sky
What we want you to do
  • Go out each evening following the day of the new moon.
  • Find a westerly facing spot with a clear view of the horizon.
  • Wait for the Sun to set, then look for the crescent moon in that part of the sky.
  • Don't look directly at the Sun, using your naked eye, binoculars or a telescope.
  • Can you see the crescent moon? Are you sure? Is it a cloud or a vapour trail?
  • Make a note of where you were, the date and time of your observation, the weather conditions and whether you saw the Moon or not.
  • Come to this website and report your observation.
  • Try and observe the crescent moon each night until you see it, reporting each observation attempt.
  • Sign up for an e-mail reminder of the next new moon and come back next month and try the same thing again.
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Permission must be granted to reproduce this material. HM Nautical Almanac Office and the UK Hydrographic Office do not accept any responsibility for any loss or damage arising from the use of information contained in the following pages.

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