# Free celestial navigation tools

Calculators and instruments from the course, free to use in your browser. Each one shows its working, so you can check your own.

- [**Sight reduction calculator**Hc, Zn and the intercept from your DR, GHA and declination, every step shown.](https://asterodos.com/sight-reduction-calculator)
- [**Noon sight calculator**The time of local noon, and your latitude from the Sun's noon altitude.](https://asterodos.com/noon-sight-calculator)
- [**Sun almanac**The Sun's GHA and declination for every hour of any date, 2026 to 2028.](https://asterodos.com/sun-almanac)
- [**Polaris latitude calculator**Latitude from the Pole Star, with the a0, a1 and a2 corrections.](https://asterodos.com/polaris-latitude-calculator)
- [**Star finder (2102-D)**A working 2102-D: the altitude and bearing of every navigational star at twilight.](https://asterodos.com/star-finder)
- [**Work your own sight**From the watch time and sextant reading to a plotted line, with the almanac built in.](https://asterodos.com/sight)
- [**Celestial sphere explorer**GHA, declination, LHA, altitude and azimuth on a sphere you can turn.](https://asterodos.com/sphere)
- [**Use Asterodos with your AI**The same tools as a connector for Claude and other assistants.](https://asterodos.com/use-with-ai)

For learning celestial navigation, not for navigating: at sea, use the official Nautical Almanac and tables, and check every position by other means.

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From Asterodos, a free interactive course in celestial navigation: https://asterodos.com/tools
For learning, not for navigating a vessel.