Horizontal Datum
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Horizontal Datum
A geodetic datum or geodetic system (also: geodetic reference datum, geodetic reference system, or geodetic reference frame) is a global datum reference or reference frame for precisely representing the position of locations on Earth or other planetary bodies by means of ''geodetic coordinates''. DatumsThe plural is not "data" in this case are crucial to any technology or technique based on spatial location, including geodesy, navigation, surveying, geographic information systems, remote sensing, and cartography. A horizontal datum is used to measure a location across the Earth's surface, in latitude and longitude or another coordinate system; a ''vertical datum'' is used to measure the elevation or depth relative to a standard origin, such as mean sea level (MSL). Since the rise of the global positioning system (GPS), the ellipsoid and datum World Geodetic System , WGS 84 it uses has supplanted most others in many applications. The WGS 84 is intended for global use, unlike most ea ...
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Datum Reference
A datum reference or just datum (plural: datumsThe plural of this word sense, sense of the word ''wikt:datum#Noun, datum'' is ''datums'' by convention, in contrast with the other senses of the word in which ''data'' usually serves as both the plural form and the mass noun counterpart.) ) is some important part of an object—such as a point (geometry), point, line (geometry), line, plane (geometry), plane, hole, set of holes, or pair of surface (mathematics), surfaces—that serves as a reference in defining the geometry of the object and (often) in measuring aspects of the actual geometry to assess how closely they match with the real versus nominal value, nominal value, which may be an ideal, standard, average, or desired value. For example, on a car's wheel, the lug nut holes define a wikt:bolt circle#Noun, bolt circle that is a datum from which the location of the rim can be defined and measured. This matters because the hub and rim need to be concentric objects, concentric to w ...
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World Geodetic System
The World Geodetic System (WGS) is a standard used in cartography, geodesy, and satellite navigation including GPS. The current version, WGS 84, defines an Earth-centered, Earth-fixed coordinate system and a geodetic datum, and also describes the associated Earth Gravitational Model (EGM) and World Magnetic Model (WMM). The standard is published and maintained by the United States National Geospatial-Intelligence Agency. History Efforts to supplement the various national surveying systems began in the 19th century with F.R. Helmert's famous book (''Mathematical and Physical Theories of Physical Geodesy''). Austria and Germany founded the ''Zentralbüro für die Internationale Erdmessung'' (Central Bureau of International Geodesy), and a series of global ellipsoids of the Earth were derived (e.g., Helmert 1906, Hayford 1910/ 1924). A unified geodetic system for the whole world became essential in the 1950s for several reasons: * International space science and the beginn ...
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John Harrison
John Harrison ( – 24 March 1776) was a self-educated English Carpentry, carpenter and clockmaker who invented the marine chronometer, a long-sought-after device for solving the History of longitude, problem of calculating longitude while at sea. Harrison's solution revolutionized navigation and greatly increased the safety of long-distance sea travel. The problem he solved was considered so important following the Scilly naval disaster of 1707 that the Parliament of Great Britain, British Parliament offered financial rewards of up to £20,000 (equivalent to £ in ) under the 1714 Longitude Act. In 1730, Harrison presented his first design, and worked over many years on improved designs, making several advances in time-keeping technology, finally turning to what were called sea watches. Harrison gained support from the Board of Longitude, Longitude Board in building and testing his designs. Toward the end of his life, he received recognition and a reward from Parliament. Harri ...
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Marine Chronometer
A marine chronometer is a precision timepiece that is carried on a ship and employed in the determination of the ship's position by celestial navigation. It is used to determine longitude by comparing Greenwich Mean Time (GMT), or in the modern world its successor Coordinated Universal Time (UTC), and the time at the current location found from observations of celestial bodies. When first developed in the 18th century, it was a major technical achievement, as accurate knowledge of the time over a long sea voyage was vital for effective navigation, lacking electronic or communications aids. The first true chronometer was the life work of one man, John Harrison, spanning 31 years of persistent experimentation and testing that revolutionized naval (and later aerial) navigation and enabling the Age of Discovery and Colonialism to accelerate. The term ''chronometer'' was coined from the Greek words '' χρόνος (chronos)'' (meaning time) and ''meter'' (meaning measure) in 1713 by ...
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Age Of Enlightenment
The Age of Enlightenment or the Enlightenment; german: Aufklärung, "Enlightenment"; it, L'Illuminismo, "Enlightenment"; pl, Oświecenie, "Enlightenment"; pt, Iluminismo, "Enlightenment"; es, La Ilustración, "Enlightenment" was an intellectual and philosophical movement that dominated Europe in the 17th and 18th centuries with global influences and effects. The Enlightenment included a range of ideas centered on the value of human happiness, the pursuit of knowledge obtained by means of reason and the evidence of the senses, and ideals such as liberty, progress, toleration, fraternity, and constitutional government. The Enlightenment was preceded by the Scientific Revolution and the work of Francis Bacon, John Locke, and others. Some date the beginning of the Enlightenment to the publication of René Descartes' ''Discourse on the Method'' in 1637, featuring his famous dictum, ''Cogito, ergo sum'' ("I think, therefore I am"). Others cite the publication of Isaac Newto ...
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Muslim
Muslims ( ar, المسلمون, , ) are people who adhere to Islam, a monotheistic religion belonging to the Abrahamic tradition. They consider the Quran, the foundational religious text of Islam, to be the verbatim word of the God of Abraham (or '' Allah'') as it was revealed to Muhammad, the main Islamic prophet. The majority of Muslims also follow the teachings and practices of Muhammad ('' sunnah'') as recorded in traditional accounts (''hadith''). With an estimated population of almost 1.9 billion followers as of 2020 year estimation, Muslims comprise more than 24.9% of the world's total population. In descending order, the percentage of people who identify as Muslims on each continental landmass stands at: 45% of Africa, 25% of Asia and Oceania (collectively), 6% of Europe, and 1% of the Americas. Additionally, in subdivided geographical regions, the figure stands at: 91% of the Middle East–North Africa, 90% of Central Asia, 65% of the Caucasus, 42% of Southeast As ...
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1870 Index Chart To GTS India-1
Year 187 ( CLXXXVII) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Quintius and Aelianus (or, less frequently, year 940 ''Ab urbe condita''). The denomination 187 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. Events By place Roman Empire * Septimius Severus marries Julia Domna (age 17), a Syrian princess, at Lugdunum (modern-day Lyon). She is the youngest daughter of high-priest Julius Bassianus – a descendant of the Royal House of Emesa. Her elder sister is Julia Maesa. * Clodius Albinus defeats the Chatti, a highly organized German tribe that controlled the area that includes the Black Forest. By topic Religion * Olympianus succeeds Pertinax as bishop of Byzantium (until 198). Births * Cao Pi, Chinese emperor of the Cao Wei state (d. 226) * G ...
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Chicago City Datum
(''City in a Garden''); I Will , image_map = , map_caption = Interactive Map of Chicago , coordinates = , coordinates_footnotes = , subdivision_type = Country , subdivision_name = United States , subdivision_type1 = State , subdivision_type2 = Counties , subdivision_name1 = Illinois , subdivision_name2 = Cook and DuPage , established_title = Settled , established_date = , established_title2 = Incorporated (city) , established_date2 = , founder = Jean Baptiste Point du Sable , government_type = Mayor–council , governing_body = Chicago City Council , leader_title = Mayor , leader_name = Lori Lightfoot ( D) , leader_title1 = City Clerk , leader_name1 = Anna Valencia ( D) , unit_pref = Imperial , area_footnotes = , area_tota ...
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