sextant

A sextant is a doubly reflecting navigation instrument used to measure the angle between any two visible objects. The principle of the instrument was first implemented around 1730 by John Hadley (1682–1744) and Thomas Godfrey (1704–1749) but it was also found later in the unpublished writings of Isaac Newton (1643–1727). The history of these and related instruments, and their forerunners, may be found in the article on reflecting instruments.

Sextant may refer to:

• Sextant (circle), a circular sector equal to one sixth of a circle, or a third of a semicircle
• Sextant, a navigation instrument
• Sextant (astronomical), a non-reflecting astronomical instrument for measuring angles
• Mural sextant, a non-reflecting, wall-mounted astronomical instrument for measuring the altitude of a celestial object
• Sextant (album), by Herbie Hancock
• Cairo Conference, held in Cairo, Egypt in 1943 codenamed SEXTANT