What device, with a scale of 60 degrees was used in marine navigation for measuring the altitude of a celestial object above the horizon?
Celestial navigation celestial navigation, referred to as the 'altitude-intercept method'. There are several other methods of celestial navigation that will also provide position-finding using sextant observations, such as the noon sight, and the more archaic lunar distance method. Joshua Slocum used the lunar distance method during the first recorded single-handed circumnavigation of the world. Unlike the altitude-intercept method, the noon sight and lunar distance methods do not require accurate knowledge of time. The altitude-intercept method of celestial navigation requires that the observer know exact Greenwich Mean Time (GMT) at the moment of his observation of the celestial body, to the second—since for
Meridian altitude Meridian altitude Meridian altitude is a method of celestial navigation to calculate an observer's latitude. It notes the angular height of an astronomical object above the horizon at culmination. Meridian altitude is the simplest calculation of celestial navigation, in which an observer determines his latitude by measuring the altitude of an astronomical object at the time of its meridian contact. A meridian contact is the moment when the object contacts the observer's meridian, i.e. the imaginary line running north–south and through the zenith, nadir, and celestial poles. This is usually done with the equinox Sun at solar noon to determine