Primilune: First Crescent Moon

Primilune helps you see the first crescent Moon on the evenings after the new moon. It tells you where to look for it, when, and with what.

A VERDICT IN FOUR COLOURS For each evening, a dot tells you how the crescent can be seen: green to the naked eye, orange with binoculars, red only with a more powerful optical aid, black if there is no visible crescent. The verdict follows Mohammad Odeh's criterion, built on 737 real observations, and the Danjon limit established by Fatoohi, Stephenson and Al-Dargazelli.

THE SKY AT TRUE SCALE The sunset, the crescent and the bright planets (Mercury, Venus, Mars, Jupiter) are drawn in their real places and at their real size. You can change the time to follow the evening. Tap the Moon: an eyepiece magnifies it.

OUTDOORS Turn your phone: the full sky shows the sunset area in large, with fingers drawn to scale, so you can measure the sky with your own hand. A compass, set against the point where the Sun went down, helps you find the direction.

YOUR HORIZON Rooftops, trees, hills: aim at the skyline with your phone, and Primilune takes your real horizon into account.

THE WORLD MAP Where the crescent can be seen that evening, all over the Earth.

EVERY LUNATION UP TO 2099 Every new moon, with the months of the Islamic calendar (named according to Umm al-Qura). Sighting the first crescent opens these months, Ramadan among them. Countries do not all decide the same way, and Primilune never says on which day a month begins.

FREE TRIAL Three days of use for free, then a single purchase unlocks the app for good, with no subscription. In countries where this sum matters, Primilune is free.

NOTHING LEAVES YOUR PHONE No account, no ads, no trackers. Everything is computed on the phone. Only searching for a place by name queries OpenStreetMap.

Three languages: English, French, Arabic.

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