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Calculation method and limits

About GoldenHourly

What we calculate — and what you should verify on location.

A local-day instrument for people who plan around natural light.

GoldenHourly helps photographers, filmmakers and anyone who loves good light plan around the sun. For any city we compute today's golden hour, blue hour, sunrise, sunset and the full twilight schedule, plus a 7-day forecast and the live position of the sun.

How the times are calculated

Calculations run live in your browser for fixed city coordinates and the selected local date. The solar-position equations follow Jean Meeus' Astronomical Algorithms and the open-source SunCalc implementation approach. We compare our phase model with the NOAA Global Monitoring Laboratory Solar Calculator as a reference.

Calculation engine 0.1.0 · Method reviewed . Automated checks cover date boundaries, daylight-saving changes, phase thresholds, and invalid windows; they do not constitute scientific certification.

These are planning estimates. Sunrise and sunset include standard atmospheric refraction (−0.833°); unusual temperature or pressure can shift the real horizon crossing by a minute or two. Weather, terrain, buildings, elevation, local access, and line-of-sight obstructions are not modeled — those conditions can change what you actually see and whether a location is usable.

Light phase definitions

GoldenHourly is independent and built as a practical planning reference for photographers and filmmakers.

Contact

Corrections, questions about the calculation method, or a city you'd like added: email cenfeng8023@gmail.com. Reports of an inaccurate time are especially welcome — include the city, the date, and what you observed, and we can check it against the reference calculators.