sextant

noun

1. an astronomical instrument used to determine latitude and longitude at sea by measuring angular distances, especially the altitudes of sun, moon, and stars.
2. (initial capital letter) Astronomy. the constellation Sextans.

noun

1. an optical instrument used in navigation and consisting of a telescope through which a sighting of a heavenly body is taken, with protractors for determining its angular distance above the horizon or from another heavenly body
2. a sixth part of a circle having an arc which subtends an angle of 60°

n.instrument for determining latitude, 1620s, from Modern Latin sextans, said to have been coined c.1600 by Danish astronomer Tycho Brahe, from Latin sextans “a sixth,” from sex “six” (see six). So called because the sextans has a graduated arc equal to a sixth part of a circle.

1. An instrument containing a graduated 60° arc and a movable pivoted arm corresponding to the radius of the arc’s circle, used in celestial navigation to measure the altitude of a celestial body in order to determine the observer’s latitude and longitude. A horizontally mounted telescope and two small mirrors are arranged so that the observer can, by moving the pivoted arm, sight the horizon and the reflected image of the celestial body in the same line, giving a reading along the arc that is used to look up the observer’s position in a published table.