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Groombridge Transit Circle
Groombridge Transit Circle was a meridian transit circle made by Edward Troughton for the English astronomer Stephen Groombridge in 1806, which Groombridge used to compile data for the star catalogue, ''Catalogue of Circumpolar Stars''. The advantage of a transit circle over a mural circle (which can measure polar distances) is that it allows measuring right ascension and declination at the same time. It had an aperture of 3.5 inches and a 5-foot focal length, mounted inside two 4 foot circles on stone piers. Groombridge used the instrument to determine the positions of over 4000 circumpolar stars. It was eventually bought by James South, and it remained at his observatory at Kensington until 1870. See also *Groombridge 1830 Groombridge 1830 (also known as 1830 Groombridge or Argelander's Star)Peters, C. A. F.; "On the Parallax of Argelander's Star", Monthly Notices of the Royal Astronomical Society, December 1853, v.50, p.302, is a star in the constellatio ... Refe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Groombridge Transit Circle
Groombridge Transit Circle was a meridian transit circle made by Edward Troughton for the English astronomer Stephen Groombridge in 1806, which Groombridge used to compile data for the star catalogue, ''Catalogue of Circumpolar Stars''. The advantage of a transit circle over a mural circle (which can measure polar distances) is that it allows measuring right ascension and declination at the same time. It had an aperture of 3.5 inches and a 5-foot focal length, mounted inside two 4 foot circles on stone piers. Groombridge used the instrument to determine the positions of over 4000 circumpolar stars. It was eventually bought by James South, and it remained at his observatory at Kensington until 1870. See also *Groombridge 1830 Groombridge 1830 (also known as 1830 Groombridge or Argelander's Star)Peters, C. A. F.; "On the Parallax of Argelander's Star", Monthly Notices of the Royal Astronomical Society, December 1853, v.50, p.302, is a star in the constellatio ... Refe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edward Troughton
Edward Troughton FRS FRSE FAS (October 1753 – 12 June 1835) was a British instrument maker who was notable for making telescopes and other astronomical instruments. Life Troughton was born at Corney, Cumberland, the youngest of six children to Francis Troughton, a husbandman on a farm, and his wife, Mary Stable. Originally raised to tend animals, Edward went to London in 1773. He then served an apprenticeship with his uncle, John Troughton (b.c.1716) alongside his elder brother, also John Troughton, and in 1779 he became his business partner and soon established himself as the top maker of navigational, surveying and astronomical instruments in Britain. They were based at 136 Fleet Street in central London. Their shop was called the "Sign of the Orrery". In 1795 he delivered what is now known as the Troughton Equatorial telescope to the Armagh Observatory, a 2-inch aperture refractor telescope mounted equatorially, and its first major instrument since its founding in 179 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stephen Groombridge
Stephen Groombridge FRS (7 January 1755 – 30 March 1832) was a British merchant and astronomer. Life He was born at Goudhurst in Kent on 7 January 1755. He succeeded when about 21 to the business in West Smithfield of a linen draper named Greenland, to whom he had been apprenticed. Later, and until 1816, he was a successful West India merchant. He lived mainly at Goudhurst, where he built a small observatory; but moved to Blackheath in 1802. In 1806, using a then new transit circle built by Edward Troughton, he began compiling a star catalogue of stars down to about eighth or ninth magnitude. He spent ten years making observations on the Groombridge Transit Circle and another ten years doing reductions of the data (correcting for refraction, instrument error and clock error). In 1827 he suffered a "severe attack of paralysis" from which he never fully recovered. Others continued the work, continuing with corrections for aberration and nutation among others. Groombridge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star Catalogue
A star catalogue is an astronomical catalogue that lists stars. In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been produced for different purposes over the years, and this article covers only some of the more frequently quoted ones. Star catalogues were compiled by many different ancient people, including the Babylonians, Greeks, Chinese, Persians, and Arabs. They were sometimes accompanied by a star chart for illustration. Most modern catalogues are available in electronic format and can be freely downloaded from space agencies' data centres. The largest is being compiled from the spacecraft Gaia and thus far has over a billion stars. Completeness and accuracy are described by the faintest limiting magnitude V (largest number) and the accuracy of the positions. Historical catalogues Ancient Near East From their existing records, it is known that the ancient Egyptians recorded the names of on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transit Circle
The meridian circle is an instrument for timing of the passage of stars across the local meridian, an event known as a culmination, while at the same time measuring their angular distance from the nadir. These are special purpose telescopes mounted so as to allow pointing only in the meridian, the great circle through the north point of the horizon, the north celestial pole, the zenith, the south point of the horizon, the south celestial pole, and the nadir. Meridian telescopes rely on the rotation of the sky to bring objects into their field of view and are mounted on a fixed, horizontal, east–west axis. The similar transit instrument, transit circle, or transit telescope is likewise mounted on a horizontal axis, but the axis need not be fixed in the east–west direction. For instance, a surveyor's theodolite can function as a transit instrument if its telescope is capable of a full revolution about the horizontal axis. Meridian circles are often called by these names, althou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mural Circle
A mural is any piece of graphic artwork that is painted or applied directly to a wall, ceiling or other permanent substrate. Mural techniques include fresco, mosaic, graffiti and marouflage. Word mural in art The word ''mural'' is a Spanish adjective that is used to refer to what is attached to a wall. The term ''mural'' later became a noun. In art, the word mural began to be used at the beginning of the 20th century. In 1906, Dr. Atl issued a manifesto calling for the development of a monumental public art movement in Mexico; he named it in Spanish ''pintura mural'' (English: ''wall painting''). In ancient Roman times, a mural crown was given to the fighter who was first to scale the wall of a besieged town. "Mural" comes from the Latin ''muralis'', meaning "wall painting". History Antique art Murals of sorts date to Upper Paleolithic times such as the cave paintings in the Lubang Jeriji Saléh cave in Borneo (40,000-52,000 BP), Chauvet Cave in Ardèche department of s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circumpolar Stars
A circumpolar star is a star that, as viewed from a given latitude on Earth, never sets below the horizon due to its apparent proximity to one of the celestial poles. Circumpolar stars are therefore visible from said location toward the nearest pole for the entire night on every night of the year (and would be continuously visible throughout the day too, were they not overwhelmed by the Sun's glare). Others are called ''seasonal'' stars. All circumpolar stars lie within a circumpolar circle whose size is determined by the observer's latitude. Specifically, the angular measure of the radius of this circle equals the observer's latitude. The closer the observer is to the North or South Pole, the larger the circumpolar circle is. Before the definition of the Arctic was formalized as the region north of the Arctic Circle which experiences the Midnight sun, it more broadly meant those places where the 'bear' constellations (Ursa Major, the Great Bear, and Ursa Minor, the Little Bear) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James South
Sir James South FRS FRSE PRAS FLS LLD (October 1785 – 19 October 1867) was a British astronomer. He was a joint founder of the Astronomical Society of London, and it was under his name, as President of the Society in 1831, that a petition was successfully submitted to obtain a Royal Charter, whereupon it became the Royal Astronomical Society. Life He was born in Southwark in London in October 1785, the son of James South, a pharmaceutical chemist. John Flint South was his younger half-brother. He originally trained as a chemist, then as a surgeon, but his interests in astronomy overtook all things. In 1821 he was elected a Fellow of the Royal Society of London and in 1822 a Fellow of the Royal Society of Edinburgh his proposer being Edward Troughton. He won the Copley Medal in 1826 and the Gold Medal of the Royal Astronomical Society in that same year. He was knighted by King William IV in 1831. Starting around 1826, James South made plans for a new, larger telescop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Groombridge 1830
Groombridge 1830 (also known as 1830 Groombridge or Argelander's Star)Peters, C. A. F.; "On the Parallax of Argelander's Star", Monthly Notices of the Royal Astronomical Society, December 1853, v.50, p.302, is a star in the constellation Ursa Major. Description It is a yellow-hued class G8 subdwarf catalogued by British astronomer Stephen Groombridge with the Groombridge Transit Circle between 1806 and the 1830s and published posthumously in his star catalog, ''Catalogue of Circumpolar Stars'' (1838). Its high proper motion was noted by Friedrich Wilhelm Argelander in 1842. It is from the Sun as measured by the Gaia spacecraft, which, as the distance is nearly 10 parsecs, means its absolute magnitude is almost equal to its apparent magnitude. It is a member of the galactic halo; such stars account for only 0.1 to 0.2 percent of the stars near the Sun. Like most halo stars, it has a low abundance of elements other than hydrogen and helium—what astronomers term a meta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
