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• Astrolabe — The astrolabe is a historical astronomical instrument used by classical astronomers, navigators, and astrologers. Its many uses included locating and predicting the positions of the Sun, Moon, planets and stars; determining local time given local …   Wikipedia

• Sextant — This article is about the sextant as used for navigation. For the astronomer s sextant, see Sextant (astronomical). : For the history and development of the sextant see Reflecting instruments A sextant is an instrument generally used to measure… …   Wikipedia