Celestial navigation. Take the sextant and shoot the Sun or the North Star.

Variation for the current day.
Used in navigation with a magnetic compass.

Celestial navigation. Take the sextant and get your Line of Position.

Great Circle and Rhumb line routes

For training or improving your skills with a sextant.

Fix by two circles of position: vector solution.
Celestial navigation.

The Nautical Almanac in your smartphone or tablet