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A diagram of a typical nautical sextant, a tool used in celestial navigation to measure the angle between two objects viewed by means of its optical sight. Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space or on the ...
In astronavigation, sight reduction is the process of deriving from a sight (in celestial navigation usually obtained using a sextant) the information needed for establishing a line of position, generally by intercept method.
The frame of a sextant is in the shape of a sector which is approximately 1 ⁄ 6 of a circle (60°), [2] hence its name (sextāns, sextantis is the Latin word for "one sixth"). "). Both smaller and larger instruments are (or were) in use: the octant, quintant (or pentant) and the (doubly reflecting) quadrant [3] span sectors of approximately 1 ⁄ 8 of a circle (45°), 1 ⁄ 5 of a circle (72 ...
By taking a sextant reading within 15 to 30 minutes prior to local noon (culmination) and noting the time, then leaving the sextant set to the same angle and subsequently observing the moment in time at which the sun passes through the sight tube on its descent from its highest altitude between a half-hour and hour later, the two times can be ...
Two years later, a specialised bubble sextant was designed for the service, which became a preferred tool for this form of navigation. [2] Typically, there would be a suspension arm mounted in the vicinity of the astrodome, upon which the sextant could be mounted via a swivel clip affixed to the top of the instrument. [3]
The first known mural sextant was constructed in Ray, Iran, by Abu-Mahmud al-Khujandi in 994. [1] To measure the obliquity of the ecliptic, al-Khujandī invented a device that he called al-Fakhri sextant (al-suds al Fakhrī), a reference to his patron, Buwayhid ruler, Fakhr al Dawla (976–997).
Astra (Sanskrit: "Weapon") is an Indian family of all weather beyond-visual-range air-to-air missile, developed by the Defence Research and Development Organisation. Different missiles of this family are capable of engaging targets at varying distances of 500 m (0.31 mi) up to 340 km (210 mi). [ 15 ]
It is an ageing A-type star of spectral class A0 III [7] located 280 ± 20 light-years away [8] from the Solar System. At the age of 385 million years, [9] it is exhausting hydrogen at its core and leaving the main sequence. γ Sextantis is the second brightest star in the constellation with an apparent magnitude of 5.05.