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 events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, t ...

and reference frame 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, outreach ...

and the

International Union of Geodesy and Geophysics The International Union of Geodesy and Geophysics (IUGG; french: Union géodésique et géophysique internationale, UGGI) is an international non-governmental organization dedicated to the scientific study of Earth and its space environment usi ...

, replacing the earlier International Polar Motion Service (IPMS) and the Earth rotation section of the Bureau International de l'Heure (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 primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...

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 subcontinent of Eurasia and it is located enti ...

and Australia. 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 observ ...

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. 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 hist ...

. 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 descr ...

s (ITRF). Related coordinate systems 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 radioisoto ...

s like GPS and Galileo:

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), Earth rotation, orientation in space, and Earth's gravity, gravity. The field also incorporates studies of how these properti ...

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 DUT1 (sometimes also written DUT) is a time correction equal to the difference between Universal Time ( UT1), which is defined by Earth's rotation, and Coordinated Universal Time (UTC), which is defined by a network of precision atomic clocks. ...

= (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