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Sextans (constellation)
Sextans is a faint, minor constellation on the celestial equator which was introduced in 1687 by Polish people, Polish astronomer Johannes Hevelius. Its name is Latin for the astronomical sextant, an instrument that Hevelius made frequent use of in his observations. Characteristics Sextans is a medium sized constellation bordering Leo (constellation), Leo to the north, touching on Hydra (constellation), Hydra to the southwest, and Crater (constellation), Crater to the southeast. The recommended three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Sex". The official constellation boundaries, as set by Belgian astronomer Eugène Joseph Delporte, Eugène Delporte in 1930, are defined by a square. In the equatorial coordinate system, the right ascension coordinates of these borders lie between and , while the declination coordinates are between +6.43° and −11.7°. Since it is close to the ecliptic plane, the Moon and p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sextant (astronomy)
In astronomy, sextants are devices depicting a sixth of a circle, used primarily for measuring the star position, position of stars. There are two types of astronomical sextants, mural instruments and frame-based instruments. They are of significant historical importance, but have been replaced over time by transit telescopes, other astrometry techniques, and satellites such as Hipparcos. Mural sextants The first known mural sextant was constructed in Ray, Iran, by Abu-Mahmud al-Khujandi in 994. To measure the Axial tilt, 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). This instrument was a sixty-degree arc on a wall aligned along a meridian (astronomy), meridian (north–south) line. Al Khujandi's instrument was larger than previous instruments; it had a radius of about twenty meters.Sevim Tekeli, Tekeli, Sevim (1958), 'Nasiruddin, Takiyudd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
