Sunrise, Sunset, and Civil Twilight

NOAA solar-position algorithm: sunrise, sunset, civil / nautical / astronomical twilight, daylight minutes.

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Formula and source

NOAA Solar Position Algorithm (SPA) calculates declination, equation of time, sunrise / sunset / civil / nautical / astronomical twilight from latitude / longitude / date.

NOAA Solar Calculator (USNO algorithm) by name; Reda & Andreas, 'Solar Position Algorithm for Solar Radiation Applications' (NREL/TP-560-34302, 2008) by name.

Audience

This tile is built for field and sar and the adjacent professions in the Field, Backcountry, and SAR group. The interactive calculator runs entirely in your browser. No account, no fee, no advertising, no tracking.

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Posture

Rough Logic answers the math question the working professional asks on the job. The site is a calm, fast, ad-free, account-free, ever-free reference. It does not interpret code. It does not replace the licensed professional. It does not store your inputs. The Authority Having Jurisdiction governs all installations and inspections.