The International Earth Rotation and Reference Systems Service (IERS), formerly the International Earth Rotation Service, is the body responsible for maintaining global

time Time is the continued sequence of existence and event (philosophy), events that occurs in an apparently irreversible process, irreversible succession from the past, through the present, into the future. It is a component quantity of various me ...

and

reference frame In physics and astronomy, a frame of reference (or reference frame) is an abstract coordinate system whose origin, orientation, and scale are specified by a set of reference points― geometric points whose position is identified both math ...

standards, notably through its Earth Orientation Parameter (EOP) and

International Celestial Reference System The International Celestial Reference System (ICRS) is the current standard celestial reference system adopted by the International Astronomical Union (IAU). Its origin is at the barycenter of the Solar System, with axes that are intended to "s ...

(ICRS) groups.

History

The IERS was established in its present form in 1987 by the

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

and the International Union of Geodesy and Geophysics, replacing the earlier International Polar Motion Service (IPMS) and the Earth rotation section of the

Bureau International de l'Heure The International Time Bureau (french: Bureau International de l'Heure, abbreviated BIH), seated at the Paris Observatory, was the international bureau responsible for combining different measurements of Universal Time. The bureau also played an i ...

(BIH). The service began operation on January 1, 1988. Since its inception, the IERS has established new bureaus including the GPS Coordinating Centre in 1990, the DORIS Coordinating Centre in 1994 and the GGF Coordinating Centre in 1998. The organization was formerly known as International Earth Rotation Service until 2003 when it formally changed its name to its present form, in which the organization chose to retain the acronym IERS.

Function

The IERS has various components located in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

and

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

. Among its other functions, the IERS is responsible for announcing

leap second A leap second is a one- second adjustment that is occasionally applied to Coordinated Universal Time (UTC), to accommodate the difference between precise time ( International Atomic Time (TAI), as measured by atomic clocks) and imprecise obser ...

s. The Sub-bureau for Rapid Service and Predictions of Earth Orientation Parameters of the IERS, located at the

United States Naval Observatory United States Naval Observatory (USNO) is a scientific and military facility that produces geopositioning, navigation and timekeeping data for the United States Navy and the United States Department of Defense. Established in 1830 as the Depo ...

, monitors the

Earth's rotation Earth's rotation or Earth's spin is the rotation of planet Earth around its own axis, as well as changes in the orientation of the rotation axis in space. Earth rotates eastward, in prograde motion. As viewed from the northern polar star Po ...

. 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 The Paris Observatory (french: Observatoire de Paris ), a research institution of the Paris Sciences et Lettres University, is the foremost astronomical observatory of France, and one of the largest astronomical centers in the world. Its histo ...

. UT1 is the non-uniform time defined based on the Earth's rotation. It defined the IERS Reference Meridian, the International Terrestrial Reference System (ITRS), and subsequent

International Terrestrial Reference Frame The International Terrestrial Reference System (ITRS) describes procedures for creating reference frames suitable for use with measurements on or near the Earth's surface. This is done in much the same way that a physical standard might be descri ...

s (ITRF). Related

coordinate system In geometry, a coordinate system is a system that uses one or more numbers, or coordinates, to uniquely determine the position of the points or other geometric elements on a manifold such as Euclidean space. The order of the coordinates is sig ...

s are used by

satellite navigation system A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioiso ...

s like GPS and

Galileo Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He was ...

WGS84 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 desc ...

and

GTRF The International Terrestrial Reference System (ITRS) describes procedures for creating reference frames suitable for use with measurements on or near the Earth's surface. This is done in much the same way that a physical standard might be descri ...

. The definitions and relationships among ITRF, ICRF and EOP are established by IERS conventions standards. , the most recent convention is the IERS Conventions (2010).

Earth orientation products

A mission of the IERS is to provide earth orientation information to the greater

geodesy Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), orientation in space, and gravity. The field also incorporates studies of how these properties change over time and equival ...

community in the form of bulletins: * Bulletin A provides a rapid turnaround service for providing current EOP and a prediction model for EOP up to a year in the future. It is released weekly. * Bulletin B provides final measurements of EOP and is released monthly. * Bulletin C provides announcements of

s * Bulletin D provides DUT1 = (UT1 − UTC) to a 0.1 second precision.

References

* Altamimi, Zuheir; Collilieux, Xavier (2013
''Reference Frames for Applications in Geosciences''
Berlin; New York: Springer , pg 57. * Gupta, Harsh K. (2011
''Encyclopedia of Solid Earth Geophysics''
Springer , pg 128. * McCarthy, Dennis D.; Seidelmann, P. Kenneth (2009
''Time: From Earth Rotation to Atomic Physics''
John Wiley & Sons , pg 290.

External links

* *
Earth Orientation Center of the IERS : data and interactive analysis (Paris Observatory)
*
IERS International Celestial Reference Frame center
{{DEFAULTSORT:International Earth Rotation And Reference Systems Service Standards organizations in France Geodesy organizations Astronomy organizations 1987 establishments in France International organizations based in France Organizations based in Paris

History

Function

Earth orientation products

See also

References

External links