The reference ellipsoid that gives the best fit to the astrogeodetic network of a particular datum, and hence does not necessarily have its center at the center of the earth. 
The reference ellipsoid that gives the best fit to the astrogeodetic network of a particular datum, and hence does not necessarily have its center at the center of the earth. 
Related Terms 
TRIAXIAL ELLIPSOIDA reference ellipsoid having three unequal axes; the shortest is the polar axis, and the two longer ones lie in the plane of the equator. 
REFERENCE ELLIPSOIDA theoretical figure whose dimensions closely approach the dimensions of the geoid; the exact dimensions of the ellipsoid are determined by various considerations of the section of the earth’s surface of concern. Also called REFERENCE SPHER OID, SPHEROID OF REFERENCE, ELLIPSOID OF REFERENCE. 
GEODETIC MERIDIANA line on a reference ellipsoid which has the same geodetic longitude at every point 
WORLD GEODETIC SYSTEMA consistent set of parameters describing the size and shape of the earth, the positions of a network of points with respect to the center of mass of the earth, transformations from major geodetic datums, and the potential of the earth (usually in terms of harmonic coefficients). It forms the common geodetic reference system for modern charts on which positions from electronic navigation systems can be plotted directly without correction. 
GEODETIC PARALLELA line on a reference ellipsoid which has the same geodetic latitude of every point. A geodetic parallel, other than the equator, is not a geodesic line. In form, it is a small circle whose plane is parallel with the plane of the geodetic equator. 
GEOCENTRIC LATITUDEThe angle at the center of the reference ellipsoid between the celestial equator and a radius vector to a point on the ellipsoid. This differs from the geographic latitude by a maximum of 11.6' of ar 
AXIS

SUPPLEMENTARY ERRORThe error of a measuring instrument arising from the fact that the values of the influence quantities differ from those corresponding to the reference conditions. 
ISOInternational Standards Organization, sets viscosity reference scales. 
DEADBANDThe variance between the reading of an operating measuring device (e.g. meter) and a reference device (e.g. prover) which is so small that there is no need for recalibration. The deadband is smaller than the tolerance range. Dead bands are expressed as both + and  around the datum line. 
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