"observations using a chronometer; these observations are reduced by solving the navigational triangle for meridian angle and require known values for altitude, latitude, and declination; the meridian angle is converted to local hour angle and compared with Greenwich hour angle. If ""Dec"" is the declination of the observed celestial body and Ho is its observed altitude, the local hour angle, ""LHA"", is obtained for a known latitude ""B"" by: formula_1 The time sight was a complement to the noon sight or latitude by Polaris in order to obtain a fix. Longitude by chronometer Longitude by chronometer is a method, in"
"scientists determined that in the Ordnance Survey system the longitude of the international Greenwich meridian was not 0° but 0°00'00.417"" (about 8 m) East. Besides the change of the reference line, imperfections of the surveying system added another discrepancy to the definition of the origin, so that the Bradley line itself is now 0°00'00.12"" East of the Ordnance Survey Zero Meridian (about 2.3m). This old astronomical prime meridian has been replaced by a more precise prime meridian. When Greenwich was an active observatory, geographical coordinates were referred to a local oblate spheroid called a datum known as a geoid, whose"
"observations were taken at the Barringun telegraph station to determine the latitude and longitude. Following these observations, the zero obelisk was erected on the banks of the Warrego River, just north of the town. From this mark, the first 5 mile chord was produced westerly and the mile posts offset from this chord to the arc (chord and arc are used when surveying latitude to allow for curvature of the earth). This continued until the survey intersected longitude 141º (now known as Cameron Corner), a distance of 285 miles 24.96 chains. That spot is marked by the Cameron Corner Survey"
"Null Island Null Island is a name for the area around the point where the prime meridian and the equator cross; in the WGS84 datum, this is at zero degrees latitude and longitude [.] (the location is in the Gulf of Guinea off the west African coast). The name 'Null Island' serves as both a joke based around the suppositional existence of an island there (in reality, only a buoy [pictured] exists there), and also as a name to which coordinates erroneously set to 0,0 are assigned in placenames databases in order to more easily find and fix them. The"
"of Mars (since about 2002) is to use planetocentric coordinates. The meridian of Mars is located at Airy-0 crater. Tidally-locked bodies have a natural reference longitude passing through the point nearest to their parent body: 0° the center of the primary-facing hemisphere, 90° the center of the leading hemisphere, 180° the center of the anti-primary hemisphere, and 270° the center of the trailing hemisphere. However, libration due to non-circular orbits or axial tilts causes this point to move around any fixed point on the celestial body like an analemma. Longitude Longitude (, ), is a geographic coordinate that specifies the"
"be negative and only S may have a fractional value. Decimal degrees Decimal degrees (DD) express latitude and longitude geographic coordinates as decimal fractions and are used in many geographic information systems (GIS), web mapping applications such as OpenStreetMap, and GPS devices. Decimal degrees are an alternative to using degrees, minutes, and seconds (DMS). As with latitude and longitude, the values are bounded by ±90° and ±180° respectively. Positive latitudes are north of the equator, negative latitudes are south of the equator. Positive longitudes are east of Prime Meridian, negative longitudes are west of the Prime Meridian. Latitude and longitude"
"sometimes known as null in mathematics. The location is used by mapping systems to trap errors. Such errors arise, for example, where an image artifact is erroneously associated to the location by software which cannot attribute a geo-position, and instead associates a latitude and longitude of ""Null,Null"" or ""0,0"". Other data mapped to the location include activity events from the Strava fitness-tracking app, apparently (as reported in January 2018 by Bellingcat) mapped to the location due to users entering ""0,0"" coordinates to disguise their real location. The only actual non-oceanic feature in that region is a moored weather and sea"
"the prime meridian or Greenwich meridian. Longitude is usually expressed in degrees (marked with °) ranging from 0° at the Greenwich meridian to 180° east and west. Sydney, for example, has a longitude of about 151° east. New York City has a longitude of 74° west. For most of history, mariners struggled to determine longitude. Longitude can be calculated if the precise time of a sighting is known. Lacking that, one can use a sextant to take a lunar distance (also called ""the lunar observation"", or ""lunar"" for short) that, with a nautical almanac, can be used to calculate the"
"Kilometre zero In many countries, Kilometre Zero (also written ""km 0"") or similar terms in other languages (also known as zero mile marker, control stations or control points) is a particular location (usually in the nation's capital city) from which distances are traditionally measured. Historically, they were markers where drivers could set their odometers to follow the directions in early guide books. One such marker is the Milliarium Aureum (""Golden Milestone"") of the Roman Empire, believed to be the literal origin for the maxim that ""all roads lead to Rome"". Argentina marks Kilometre Zero with a monolith in Plaza Congreso"
"the location of a place on Earth east or west of the Prime Meridian. Each degree of longitude is sub-divided into 60 minutes, each of which is divided into 60 seconds. A longitude is thus specified in sexagesimal notation as 23° 27′ 30″ E. For higher precision, the seconds are specified with a decimal fraction. An alternative representation uses degrees and minutes, where parts of a minute are expressed in decimal notation with a fraction, thus: 23° 27.5′ E. Degrees may also be expressed as a decimal fraction: 23.45833° E. For calculations, the angular measure may be converted to radians,"
"Department, south of Nueva Palmira. Kilometre zero In many countries, Kilometre Zero (also written ""km 0"") or similar terms in other languages (also known as zero mile marker, control stations or control points) is a particular location (usually in the nation's capital city) from which distances are traditionally measured. Historically, they were markers where drivers could set their odometers to follow the directions in early guide books. One such marker is the Milliarium Aureum (""Golden Milestone"") of the Roman Empire, believed to be the literal origin for the maxim that ""all roads lead to Rome"". Argentina marks Kilometre Zero with"
"""a"", ""b"" and ""f"". They are listed in ellipse. A primary use of reference ellipsoids is to serve as a basis for a coordinate system of latitude (north/south), longitude (east/west), and ellipsoidal height. For this purpose it is necessary to identify a ""zero meridian"", which for Earth is usually the Prime Meridian. For other bodies a fixed surface feature is usually referenced, which for Mars is the meridian passing through the crater Airy-0. It is possible for many different coordinate systems to be defined upon the same reference ellipsoid. The longitude measures the rotational angle between the zero meridian and"
"strip is indeed at ""astronomical"" longitude zero degrees, zero minutes, and zero seconds—but GPS receivers show ""geodetic"" longitude, which equalises the higher mass, otherwise seen, of the eastern hemisphere (specifically per Standard ITRF/WGS 84). Before the establishment of a common meridian, most maritime countries established their own prime meridian, usually passing through the country in question. In 1721, Great Britain established its own meridian passing through an early transit circle at the newly established Royal Observatory at Greenwich. The meridian was moved around 10 metres or so east on three occasions as transit circles with newer and better instruments were"
"Longitude is a number preceded by a sign character. A plus sign (codice_2) denotes east longitude or the prime meridian, and a minus sign (codice_3) denotes west longitude or 180° meridian (opposite of the prime meridian). Rules about the number of digits are the same as for latitude. The CRS identifier begins with ""CRS"". There are three styles: The example of original Annex H always use ""CRSWGS_84"". ISO 6709 ISO 6709 ""Standard representation of geographic point location by coordinates"" is the international standard for representation of latitude, longitude and altitude for geographic point locations. The first edition (ISO 6709:1983) was"
"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 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"". 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)"
"Zero Milestone The Zero Milestone is a zero mile marker monument in Washington, D.C. intended as the initial milestone from which all road distances in the United States should be reckoned when it was built. At present, only roads in the Washington, D.C. area have distances measured from it. The monument stands just south of the White House at the north edge of The Ellipse, within President's Park. Atop the monument is a bronze 16-point compass rose with a very small worn-down pyramid at its center whose top serves as a National Geodetic Survey benchmark (HV1847). Designed by Washington architect"
"observation buoy, part of the PIRATA system operated jointly by the United States, France, and Brazil. The depth at this place is around . Null Island Null Island is a name for the area around the point where the prime meridian and the equator cross; in the WGS84 datum, this is at zero degrees latitude and longitude [.] (the location is in the Gulf of Guinea off the west African coast). The name 'Null Island' serves as both a joke based around the suppositional existence of an island there (in reality, only a buoy [pictured] exists there), and also as"
"Latitude In geography, latitude is a geographic coordinate that specifies the north–south position of a point on the Earth's surface. Latitude is an angle (defined below) which ranges from 0° at the Equator to 90° (North or South) at the poles. Lines of constant latitude, or ""parallels"", run east–west as circles parallel to the equator. Latitude is used together with longitude to specify the precise location of features on the surface of the Earth. On its own, the term latitude should be taken to be the ""geodetic latitude"" as defined below. Briefly, geodetic latitude at a point is the angle"
"degrees, minutes, and seconds. For example, a longitude of is 19.933° east of the start of the sign Leo. Since Leo begins 120° from the vernal equinox, the longitude in modern form is . In China, ecliptic longitude is measured using 24 Solar terms, each of 15° longitude, and are used by Chinese lunisolar calendars to stay synchronized with the seasons, which is crucial for agrarian societies. A rectangular variant of ecliptic coordinates is often used in orbital calculations and simulations. It has its origin at the center of the Sun (or at the barycenter of the Solar System), its"
"of the same latitude trace circles on the surface of Earth called 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 of all geographic coordinate systems. The Equator divides the globe into Northern and Southern Hemispheres. The ""longitude"" (abbreviation: Long., λ, or lambda) of a point on Earth's surface is the angle east or west of a reference meridian to another meridian that passes through that point. All meridians are halves of great"
"longitude and latitude of the earth. These instruments also were typically effected by local gravity, which paired well with existing technologies such as the magnetic meridian. Tools of Measurement Meridian (geography) A (geographical) meridian (or line of longitude) is the half of an imaginary great circle on the Earth's surface, terminated by the North Pole and the South Pole, connecting points of equal longitude, as measured in angular degrees east or west of the Prime Meridian. The position of a point along the meridian is given by that longitude and its latitude, measured in angular degrees north or south of"
"Decimal degrees Decimal degrees (DD) express latitude and longitude geographic coordinates as decimal fractions and are used in many geographic information systems (GIS), web mapping applications such as OpenStreetMap, and GPS devices. Decimal degrees are an alternative to using degrees, minutes, and seconds (DMS). As with latitude and longitude, the values are bounded by ±90° and ±180° respectively. Positive latitudes are north of the equator, negative latitudes are south of the equator. Positive longitudes are east of Prime Meridian, negative longitudes are west of the Prime Meridian. Latitude and longitude are usually expressed in that sequence, latitude before longitude. The"
"the measured point. By convention for the Earth, Moon, and Sun it is expressed in degrees ranging from −180° to +180° For other bodies a range of 0° to 360° is used. The latitude measures how close to the poles or equator a point is along a meridian, and is represented as an angle from −90° to +90°, where 0° is the equator. The common or ""geodetic latitude"" is the angle between the equatorial plane and a line that is normal to the reference ellipsoid. Depending on the flattening, it may be slightly different from the ""geocentric (geographic) latitude"", which"
"is a monument locating the geographical centre of colonial India in the city of Nagpur, Maharashtra, or that the Zero Mile Stone was erected by the British to use this point to measure all the distances. Kilometre zero of Indonesia is marked by the monument located in Weh Island, the northernmost and westernmost point of Indonesia. In Ireland distances from Dublin are measured from the General Post Office on the city’s main thoroughfare, O’Connell Street. For distances in Northern Ireland, Donegall Square is considered the centre of Belfast. The Italian Kilometre Zero is located on the top of the Capitoline"
"increased the precision with which objects could be located on the surface of Mars, the center of a 500 m circular crater was considered to be insufficiently precise for exact measurements. The IAU Working Group on Cartographic Coordinates and Rotational Elements therefore recommended setting the longitude of the Viking 1 lander, for which there were extensive radiometric tracking data, as marking the standard longitude of 47.95137° west. This deﬁnition maintains the position of the center of Airy-0 at 0° longitude, within the tolerance of current cartographic uncertainties. Observers of Martian topography will notice a dichotomy between the northern and southern"
"Airy-0 Airy-0 is a crater on Mars whose location defined the position of the prime meridian of that planet. It is about across and lies within the larger crater Airy in the region Sinus Meridiani. The IAU Working Group on Cartographic Coordinates and Rotational Elements has now recommended setting the longitude of the Viking 1 lander (47°.95137 west) as the standard. This deﬁnition maintains the position of the center of Airy-0 at 0° longitude, within the tolerance of current cartographic uncertainties. Merton Davies tied this crater into an extensive geodetic control network of the planet Mars based on Mariner 9"
"latitude. Longitudinal slices are numbered 1 (180-174°West) through 60 (174-180°East). Latitudinal slices are named NA (0-4°North) through NV (84-88°North) and SA (0-4°South) through SV (84-88°South). For example Due to shortening of longitudinal distances with increasing latitude, longitudinal span beyond 60 degrees latitude doubles to twelve degrees. Beyond 76 degrees it doubles again to 24 degrees. This indexing system outlived the international project and is still used in national and international mapping programs by Australia, Russia and the United States. International Map of the World The International Map of the World (also called the Millionth Map, after its scale of 1:1000000)"
"In his earlier work on sea clocks, Harrison was continually assisted, both financially and in many other ways, by George Graham, the watchmaker and instrument maker. Harrison was introduced to Graham by the Astronomer Royal Edmond Halley, who championed Harrison and his work. This support was important to Harrison, as he was supposed to have found it difficult to communicate his ideas in a coherent manner. Longitude fixes the location of a place on Earth east or west of a north-south line called the prime meridian. It is given as an angular measurement that ranges from 0° at the prime"
"Meridian (geography) A (geographical) meridian (or line of longitude) is the half of an imaginary great circle on the Earth's surface, terminated by the North Pole and the South Pole, connecting points of equal longitude, as measured in angular degrees east or west of the Prime Meridian. The position of a point along the meridian is given by that longitude and its latitude, measured in angular degrees north or south of the Equator. Each meridian is perpendicular to all circles of latitude. Each is also the same length, being half of a great circle on the Earth's surface and therefore"
"from 1 at the equator to 0 at the poles, which measures how circles of latitude shrink from the equator to a point at the pole, so the length of a degree of longitude decreases likewise. This contrasts with the small (1%) increase in the length of a degree of latitude (north-south distance), equator to pole. The table shows both for the WGS84 ellipsoid with = and = . Note that the distance between two points 1 degree apart on the same circle of latitude, measured along that circle of latitude, is slightly more than the shortest (geodesic) distance between"
"celestial longitude and latitude, are used to specify positions of bodies on the celestial sphere with respect to the ecliptic. Longitude is measured positively eastward 0° to 360° along the ecliptic from the vernal equinox, the same direction in which the Sun appears to move. Latitude is measured perpendicular to the ecliptic, to +90° northward or −90° southward to the poles of the ecliptic, the ecliptic itself being 0° latitude. For a complete spherical position, a distance parameter is also necessary. Different distance units are used for different objects. Within the Solar System, astronomical units are used, and for objects"
"of the details and raised donations for the design and construction. The permanent Zero Milestone was dedicated in a ceremony on June 4, 1923. Zero Milestone The Zero Milestone is a zero mile marker monument in Washington, D.C. intended as the initial milestone from which all road distances in the United States should be reckoned when it was built. At present, only roads in the Washington, D.C. area have distances measured from it. The monument stands just south of the White House at the north edge of The Ellipse, within President's Park. Atop the monument is a bronze 16-point compass"
"it in several places for political reasons, including between far eastern Russia and the far western Aleutian Islands. The combination of these two components specifies the position of any location on the surface of Earth, without consideration of altitude or depth. The grid formed by lines of latitude and longitude is known as a ""graticule"". The origin/zero point of this system is located in the Gulf of Guinea about south of Tema, Ghana. On the GRS80 or WGS84 spheroid at sea level at the Equator, one latitudinal second measures ""30.715 metres"", one latitudinal minute is ""1843 metres"" and one latitudinal"