/astroplan — Astrophotography Planner
Plan a night of astrophotography for a place, date and camera rig: the longest exposure before star trails show (the 500 rule and the sharper NPF rule), the astronomical darkness window for the night, and how the moon will interfere. Times are shown in your device's timezone.
Max exposure before star trails
500 rule
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500 ÷ (crop × focal length). A quick rule of thumb based on focal length alone.
NPF rule (recommended)
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Also accounts for aperture and pixel pitch — a sharper estimate on modern high-resolution sensors.
Short exposures mean fewer photons per frame — shoot many short frames at a higher ISO and stack them for a cleaner, less noisy result: /astrostack.
Astronomical darkness
Astro dusk
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Astro dawn
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Dark duration
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Moon interference
Illumination
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Phase
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Moon rise / set tonight
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Dark & moonless window: —
twilight dark & moonless moon up