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| | Hello from Germany. I'm glad to came here. My first name is Dani. <br>I live in a small town called Dessau in east Germany.<br>I was also born in Dessau 26 years ago. Married in February year 2003. I'm working at the backery.<br><br>Also visit my page :: [http://helpitlanka.blogspot.co.nz/2012/08/password-strength.html fifa 15 coin Generator] |
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| [[File:Sphere filled blue.svg|thumb|200px|right|A graticule on a [[sphere]] or an [[ellipsoid]]. The lines from pole to pole are lines of constant [[longitude]], or '''meridians'''. The circles parallel to the equator are lines of constant latitude, or '''parallels'''. The graticule determines the latitude and longitude of position on the surface.]]
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| {{Geodesy}}
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| [[File:Latitude and Longitude of the Earth.svg|thumb|300px|Latitude and Longitude of the Earth]]
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| A '''geographic coordinate system''' is a [[coordinate system]] that enables every location on the Earth to be specified by a set of numbers or letters. The coordinates are often chosen such that one of the numbers represents [[altitude|vertical position]], and two [[n-vector|or three]] of the numbers represent [[horizontal position representation|horizontal position]]. A common choice of coordinates is [[latitude]], [[longitude]] and [[elevation]].<ref name=OSGB>[http://www.ordnancesurvey.co.uk/oswebsite/gps/docs/A_Guide_to_Coordinate_Systems_in_Great_Britain.pdf A Guide to coordinate systems in Great Britain] v1.7 October 2007 D00659 accessed 14.4.2008</ref>
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| ==Geographic latitude and longitude==
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| {{Main|Latitude|Longitude}}
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| The "latitude" (abbreviation: Lat., [[φ]], or phi) of a point on the Earth's surface is the angle between the equatorial plane and the straight line that passes through that point and is [[Normal (geometry)|normal]] to the surface of a [[reference ellipsoid]] which approximates the [[Figure of the Earth|shape of the Earth]].<ref group=n>The surface of the Earth is closer to an [[Earth ellipsoid|ellipsoid]] than to a sphere, as its equatorial diameter is larger than its north-south axis.</ref> This line passes a few kilometers away from the center of the Earth except at the poles and the equator where it passes through Earth's center.<ref group=n>The greatest distance between an ellipsoid normal and the center of the Earth is 21.9 km at a latitude of 45°, using [[Earth radius#Radius at a given geodetic latitude]] and [[Latitude#Numerical comparison of auxiliary latitudes]]: {{nowrap|1= (6367.5 km)×tan(11.67')=21.9 km.}}</ref> Lines joining points of the same latitude trace circles on the surface of the Earth called [[circle of latitude|parallels]], as they are parallel to the equator and to each other. The [[north pole]] is 90° N; the [[south pole]] is 90° S. The 0° parallel of latitude is designated the [[equator]], the [[fundamental plane (spherical coordinates)|fundamental plane]] of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres.
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| The "longitude" (abbreviation: Long., [[λ]], or lambda) of a point on the Earth's surface is the angle east or west from a reference [[meridian (geography)|meridian]] to another meridian that passes through that point. All meridians are halves of great [[ellipse]]s (often improperly called [[great circle]]s), which converge at the north and south poles.
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| A line passing near the [[Royal Observatory, Greenwich]] (a suburb of London, UK) has been chosen as the international zero-longitude reference line, the [[Prime Meridian]]. Places to the east are in the eastern hemisphere, and places to the west are in the western hemisphere. The [[Antipodes|antipodal]] meridian of Greenwich is both 180°W and 180°E. The zero/zero point is located in the Gulf of Guinea about 625 km south of Tema, Ghana.
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| In 1884 the United States hosted the [[International Meridian Conference]] and twenty-five nations attended. Twenty-two of them agreed to adopt the location of Greenwich as the zero-reference line. The [[Dominican Republic]] voted against the adoption of that motion, while France and [[Brazil]] abstained.<ref>{{cite web|author=Greenwich 2000 Limited |url=http://wwp.millennium-dome.com/info/conference.htm |title=The International Meridian Conference |publisher=Wwp.millennium-dome.com |date=9 June 2011 |accessdate=31 October 2012}}</ref> To date, there exist organizations around the world which continue to use historical prime meridians which existed before the acceptance of Greenwich became common-place.<ref group=n>The French Institut Géographique National (IGN) maps still use longitude from a meridian passing through Paris, along with longitude from Greenwich.</ref>
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| The combination of these two components specifies the position of any location on the planet, but does not consider [[altitude]] nor [[:wikt:depth|depth]]. This latitude/longitude "webbing" is known as the ''graticule''.
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| ==UTM and UPS systems==
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| {{Main|Universal Transverse Mercator|Universal Polar Stereographic}}
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| The [[Universal Transverse Mercator]] (UTM) and [[Universal Polar Stereographic]] (UPS) coordinate systems both use a metric-based cartesian grid laid out on a [[Map projection#Projections by preservation of a metric property|conformally projected]] surface to locate positions on the surface of the Earth. The UTM system is not a single [[map projection]] but a series of map projections, one for each of sixty 6-degree bands of longitude. The UPS system is used for the polar regions, which are not covered by the UTM system.
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| ==Stereographic coordinate system==
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| During medieval times, the stereographic coordinate system was used for navigation purposes.{{Citation needed|date=December 2007}} The stereographic coordinate system was superseded by the latitude-longitude system.
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| Although no longer used in navigation, the stereographic coordinate system is still used in modern times to describe crystallographic orientations in the fields of [[crystallography]], [[mineralogy]] and materials science.{{Citation needed|date=December 2007}}
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| ==Geodetic height==
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| To completely specify a location of a topographical feature on, in, or above the Earth, one has to also specify the vertical distance from the centre of the Earth, or from the surface of the Earth. Because of the ambiguity of "surface" and "vertical", it is more commonly expressed relative to a precisely defined [[datum (geodesy)|vertical datum]] which holds fixed some known point. Each country has defined its own datum. For example, in the United Kingdom the reference point is [[Newlyn]], while in Canada, Mexico and the United States, the point is near [[Rimouski]], [[Quebec]], [[Canada]]. The distance to Earth's centre can be used both for very deep positions and for positions in space.<ref name=OSGB/>
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| ==Cartesian coordinates==
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| Every point that is expressed in ellipsoidal coordinates can be expressed as an {{nowrap|x y z}} ([[Cartesian coordinate|Cartesian]]) coordinate. Cartesian coordinates simplify many mathematical calculations. The origin is usually the center of mass of the earth, a point close to the Earth's [[Figure of the Earth|center of figure]].
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| With the origin at the center of the ellipsoid, the conventional setup is the expected right-hand:
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| Z-axis along the axis of the ellipsoid, positive northward<br>
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| X- and Y-axis in the plane of the equator, X-axis positive toward 0 degrees longitude and Y-axis positive toward 90 degrees east longitude.
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| An example is the [http://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=aa3449 NGS data] for a brass disk near Donner Summit, in California. Given the dimensions of the ellipsoid, the conversion from lat/lon/height-above-ellipsoid coordinates to X-Y-Z is straightforward—calculate the X-Y-Z for the given lat-lon on the surface of the ellipsoid and add the X-Y-Z vector that is perpendicular to the ellipsoid there and has length equal to the point's height above the ellipsoid. The reverse conversion is harder: given X-Y-Z we can immediately get longitude, but no closed formula for latitude and height exists. <!--, However, --> See "[[Geodetic system#Geodetic to/from ECEF coordinates|Geodetic system]]." Using Bowring's formula in 1976 ''Survey Review'' the first iteration gives latitude correct within <math>10^{-11}</math> degree as long as the point is within 10000 meters above or 5000 meters below the ellipsoid.
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| ==Shape of the Earth==
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| {{Main|Figure of the Earth|Reference ellipsoid}}
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| The Earth is not a sphere, but an irregular shape approximating a [[Earth ellipsoid|biaxial ellipsoid]]. It is nearly spherical, but has an equatorial bulge making the radius at the equator about 0.3% larger than the radius measured through the poles. The shorter axis approximately coincides with axis of rotation. Map-makers choose the true ellipsoid that best fits their need for the area they are mapping. They then choose the most appropriate mapping of the spherical coordinate system onto that ellipsoid. In the United Kingdom there are three common latitude, longitude, height systems in use. The system used by GPS, [[World Geodetic System|WGS84]], differs at Greenwich from the one used on published maps [[OSGB36]] by approximately 112m. The military system [[ED50]], used by [[NATO]], differs by about 120m to 180m.<ref name=OSGB/>
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| Though early navigators thought of the sea as a flat surface that could be used as a vertical datum, this is far from reality. The Earth has a series of layers of equal [[potential energy]] within its [[gravitational field]]. Height is a measurement at right angles to this surface, roughly toward the centre of the Earth, but local variations make the equipotential layers irregular (though roughly ellipsoidal). The choice of which layer to use for defining height is arbitrary. The reference height that has been chosen is the one closest to the average height of the world's oceans. This is called the [[geoid]].<ref name=OSGB/><ref name=USDOD>[http://www.ngs.noaa.gov/PUBS_LIB/Geodesy4Layman/geo4lay.pdf DMA Technical Report] Geodesy for the Layman, The Defense Mapping Agency, 1983</ref>
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| The Earth is not static as points move relative to each other due to continental plate motion, subsidence, and diurnal movement caused by the [[Moon]] and the [[tide]]s. The daily movement can be as much as a metre. Continental movement can be up to {{nowrap|10 cm}} a year, or {{nowrap|10 m}} in a century. A [[weather system]] high-pressure area can cause a sinking of {{nowrap|5 mm}}. [[Scandinavia]] is rising by {{nowrap|1 cm}} a year as a result of the melting of the ice sheets of the [[Quaternary glaciation|last ice age]], but neighbouring [[Scotland]] is rising by only {{nowrap|0.2 cm}}. These changes are insignificant if a local datum is used, but are statistically significant if the global GPS datum is used.<ref name=OSGB/>
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| ==Expressing latitude and longitude as linear units==
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| {{main|Length of a degree of latitude|Length of a degree of longitude}}
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| On the GRS80 or WGS84 spheroid at [[sea level]] at the equator, one latitudinal second measures ''30.715 [[metre]]s'', one latitudinal minute is ''1843 metres'' and one latitudinal degree is ''110.6 kilometres''. The circles of longitude, meridians, meet at the geographical poles, with the west-east width of a second naturally decreasing as latitude increases. On the [[equator]] at sea level, one longitudinal{{Contradiction-inline|reason=Longitudinal distance would remain relatively constant relative to angle; that is one minute of longitude at N80° would be very similar to one minute of longitude at N10°.|date=July 2012}} second measures ''30.92 metres'', a longitudinal minute is ''1855 metres'' and a longitudinal degree is ''111.3 kilometres''. At 30° a longitudinal second is ''26.76 metres'', at Greenwich (51° 28' 38" N) ''19.22 metres'', and at 60° it is ''15.42 metres''.
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| On the WGS84 spheroid, the length in meters of a degree of latitude at latitude φ (that is, the distance along a north-south line from latitude (φ - 0.5) degrees to (φ + 0.5) degrees) is about
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| :::::<math>111132.954 - 559.822\, \cos 2\varphi + 1.175\, \cos 4\varphi</math>
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| (Those coefficients can be improved, but as they stand the distance they give is correct within a centimeter.)
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| To estimate the length of a longitudinal degree at latitude <math>\scriptstyle{\phi}\,\!</math> we can assume a spherical Earth (to get the width per minute and second, divide by 60 and 3600, respectively):
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| :::::<math> \frac{\pi}{180}M_r\cos \phi \!</math>
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| where [[Earth radius#Meridional Earth radius|Earth's average meridional radius]] <math>\scriptstyle{M_r}\,\!</math> is {{nowrap|6,367,449 m}}. Since the Earth is not spherical that result can be off by several tenths of a percent; a better approximation of a longitudinal degree at latitude <math>\scriptstyle{\phi}\,\!</math> is
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| :::::<math>\frac{\pi}{180}a \cos \beta \,\!</math>
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| where Earth's equatorial radius <math>a</math> equals ''6,378,137 m'' and <math>\scriptstyle{\tan \beta = \frac{b}{a}\tan\phi}\,\!</math>; for the GRS80 and WGS84 spheroids, b/a calculates to be 0.99664719. (<math>\scriptstyle{\beta}\,\!</math> is known as the [[Latitude#Reduced (or parametric) latitude|reduced (or parametric) latitude]]). Aside from rounding, this is the exact distance along a parallel of latitude; getting the distance along the shortest route will be more work, but those two distances are always within 0.6 meter of each other if the two points are one degree of longitude apart.
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| {| class="wikitable"
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| |+ '''Longitudinal length equivalents at selected latitudes'''
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| |-
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| ! style="width:100px;"|Latitude
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| ! style="width:150px;"|City
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| ! style="width:100px;"|Degree
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| ! style="width:100px;"|Minute
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| ! style="width:100px;"|Second
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| ! style="width:100px;"|±0.0001°
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| |-
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| |60°||[[Saint Petersburg]]|| style="text-align:center;" | 55.80 km|| style="text-align:center;" | 0.930 km|| style="text-align:center;" | 15.50 m || style="text-align:center;" | 5.58 m
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| |-
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| |51° 28' 38" N||[[Greenwich]]|| style="text-align:center;" | 69.47 km|| style="text-align:center;" | 1.158 km|| style="text-align:center;" | 19.30 m|| style="text-align:center;" | 6.95 m
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| |-
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| |45°||[[Bordeaux]]|| style="text-align:center;" | 78.85 km|| style="text-align:center;"| 1.31 km|| style="text-align:center;" | 21.90 m|| style="text-align:center;" | 7.89 m
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| |-
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| |30°||[[New Orleans]]|| style="text-align:center;" | 96.49 km|| style="text-align:center;"| 1.61 km|| style="text-align:center;" | 26.80 m|| style="text-align:center;" | 9.65 m
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| |-
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| |0°||[[Quito]]|| style="text-align:center;"| 111.3 km || style="text-align:center;"| 1.855 km || style="text-align:center;"| 30.92 m || style="text-align:center;"| 11.13 m
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| |}
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| <!--The equator is the [[fundamental plane (spherical coordinates)|fundamental plane]] of all geographic coordinate systems. All spherical coordinate systems define such a fundamental plane.-->
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| ==Datums often encountered==
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| {{Main|Geodetic system|Datum (geodesy)}}
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| Latitude and longitude values can be based on different geodetic systems or [[datum (geodesy)|datums]], the most common being [[World Geodetic System|WGS 84]], a global datum used by all GPS equipment.<ref group=n>WGS 84 is the ''default'' datum used in most GPS equipment, but other datums can be selected.</ref> Other datums are significant because they were chosen by a national cartographical organisation as the best method for representing their region, and these are the datums used on printed maps. The latitude and longitude on a map may not be the same as on a GPS receiver. Coordinates from the [[Figure of the Earth#Historical Earth ellipsoids|mapping system]] can sometimes be roughly changed into another datum using a simple [[translation]]. For example, to convert from ETRF89 (GPS) to the [[Irish grid reference system|Irish Grid]] add 49 metres to the east, and subtract 23.4 metres from the north.<ref name=irish>{{cite web |url=http://www.osi.ie/GetAttachment.aspx?id=25113681-c086-485a-b113-bab7c75de6fa |title=Making maps compatible with GPS |publisher=Government of Ireland 1999 |accessdate= 15 April 2008 |archiveurl=//web.archive.org/web/20110721130505/http://www.osi.ie/GetAttachment.aspx?id=25113681-c086-485a-b113-bab7c75de6fa |archivedate=21 July 2011 |deadurl=yes}}</ref> More generally one datum is changed into any other datum using a process called [[Helmert transformation]]s. This involves converting the spherical coordinates into Cartesian coordinates and applying a seven parameter transformation (translation, three-dimensional [[rotation]]), and converting back.<ref name=OSGB/>
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| In popular GIS software, data projected in latitude/longitude is often represented as a 'Geographic Coordinate System'. For example, data in latitude/longitude if the datum is the [[NAD83|North American Datum of 1983]] is denoted by 'GCS North American 1983'.
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| ==Geostationary coordinates==
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| [[Geostationary]] satellites (e.g., television satellites) are over the [[equator]] at a specific point on Earth, so their position related to Earth is expressed in [[longitude]] degrees only. Their [[latitude]] is always zero, that is, over the equator.
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| ==On other celestial bodies==
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| Similar coordinate systems are defined for other celestial bodies such as:
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| * A similarly well-defined system [[Reference ellipsoid#Ellipsoids for other planetary bodies|based on the reference ellipsoid]] for [[Mars]].
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| * [[Selenographic coordinates]] for the [[Moon]]
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| ==See also==
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| {{Portal|Atlas}}
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| {{div col|colwidth=30em}}
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| * [[Automotive navigation system]]
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| * [[Digital Earth Reference Model]] (DERM)
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| * [[Geographic coordinate conversion]]
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| * [[Geocoding]]
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| * [[Geographical distance]]
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| * [[Geotagging]]
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| * [[Great-circle distance]] the shortest distance between any two points on the surface of a sphere.
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| * [[Lambert conformal conic projection]] Lambert coordinate system
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| * [[Tropic of Cancer]]
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| * [[Tropic of Capricorn]]
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| {{div col end}}
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| ==Notes==
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| {{reflist|group=n|30em}}
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| ==References==
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| {{Reflist|30em}}
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| * ''Portions of this article are from Jason Harris' "Astroinfo" which is distributed with [[KStars]], a desktop planetarium for [[Linux]]/[[KDE]]. See [http://edu.kde.org/kstars/index.phtml]''
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| ==External links==
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| {{Commons category}}
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| * [http://math.rice.edu/~lanius/pres/map/mapcoo.html Mathematics Topics-Coordinate Systems]
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| * [https://www.cia.gov/library/publications/the-world-factbook/index.html Geographic coordinates of countries (CIA World Factbook)]
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| * [http://www.whitemaps.com Coordinates conversion tool (batch conversions of Decimal, DM, DMS and UTM)]
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| * [http://www.fcc.gov/mb/audio/bickel/DDDMMSS-decimal.html FCC coordinates conversion tool (DD to DMS/DMS to DD)]
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| * [http://www.sunearthtools.com/dp/tools/conversion.php Coordinate converter, formats: DD, DMS, DM]
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| * [http://www.doogal.co.uk/LatLong.php Latitude and Longitude]
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| {{Geographical coordinates}}
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| {{DEFAULTSORT:Geographic Coordinate System}}
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| [[Category:Geographic coordinate systems|*]]
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| [[Category:Cartography]]
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| [[Category:Navigation]]
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| [[Category:Geodesy]]
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| [[Category:Geocodes]]
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