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In geodesy and astrometry, earth orientation parameters (EOP) describe irregularities in the rotation of planet Earth.EOP provide the rotational transform from the International Terrestrial Reference System (ITRS) to the International Celestial Reference System (ICRS), or vice versa, as a function of time.
The Sub-bureau for Rapid Service and Predictions of Earth Orientation Parameters of the IERS, located at the United States Naval Observatory, monitors the Earth's rotation. Part of its mission involves the determination of a time scale based on the current rate of the rotation of the Earth. Other services of IERS are at the Paris Observatory.
Constructed with input data under the form of time series of station positions and Earth Orientation Parameters. [5] This version introduces extra parameters to describe the year-periodic motion of the stations: A (amplitude) and φ (phase) per-axis. This sort of seasonal variation has an amplitude of around 1 cm and is attributed to non-tidal ...
Earth's rotation period relative to the Sun (solar noon to solar noon) is its true solar day or apparent solar day. [26] It depends on Earth's orbital motion and is thus affected by changes in the eccentricity and inclination of Earth's orbit. Both vary over thousands of years, so the annual variation of the true solar day also varies.
A data set which describes the global average of the Earth's surface curvature is called the mean Earth Ellipsoid. It refers to a theoretical coherence between the geographic latitude and the meridional curvature of the geoid. The latter is close to the mean sea level, and therefore an ideal Earth ellipsoid has the same volume as the geoid.
Earth orientation parameters 33: UTC parameters 35: GPS/GNSS time offset The CNAV data is an upgraded version of the original NAV navigation message. It contains ...
Current and historic polar motion data is available from the International Earth Rotation and Reference Systems Service's Earth orientation parameters. [19] Note in using this data that the convention is to define p x to be positive along 0° longitude and p y to be positive along 90°E longitude. [20]
ETRS89 parameters [6] CS_NAME ETRS89 SRID: 4258 AUTH_NAME EPSG. See 3D CRS for original information source Coordinate System Type Geographic Datum European Terrestrial Reference System 1989 (EPSG ID 4258) Spheroid GRS 1980 (EPSG ID 7019) Semi-Major Axis 6378137.000 Semi-Minor Axis 6356752.314140 Inverse flattening 298.257222101 Prime Meridian ...