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International Earth Rotation and Reference Systems Service

The IERS logo
Abbreviation	IERS
Website	www.iers.org

The International Earth Rotation and Reference Systems Service (IERS), formerly the International Earth Rotation Service, is the body responsible for maintaining global time and reference frame standards, notably through its Earth Orientation Parameter (EOP) and International Celestial Reference System (ICRS) groups.

History

The IERS was established in its present form in 1987 by the International Astronomical Union 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 (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 Global Geophysical Fluids 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, Europe and Australia. Among its other functions, the IERS is responsible for announcing leap seconds.

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.

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 Frames (ITRF). Related coordinate systems are used by satellite navigation systems like GPS and Galileo: WGS84 and GTRF. The definitions and relationships among ITRF, ICRF and EOP are established by IERS conventions standards. As of 2022, 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 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 leap seconds.
• Bulletin D provides DUT1 = (UT1 − UTC) to a 0.1 second precision.

See also

• Astrometry
• International Atomic Time
• Coordinated Universal Time
• International Terrestrial Reference System and Frame
• Leap second
• International Celestial Reference System and its realizations
• Earth rotation, ΔT
• IERS Reference Meridian
• List of astronomical societies

References

1. "IERS Conventions Centre". IERS. Retrieved 5 July 2022.
2. "Earth Orientation Center". Observatoire de Paris. Retrieved 2 August 2016.
3. "IERS Bulletins". IERS. Retrieved 5 July 2022.

Further reading

• Altamimi, Zuheir; Collilieux, Xavier (2013). Reference Frames for Applications in Geosciences. Springer Science & Business Media. p. 57. ISBN 978-3-642-32998-2.
• Gupta, Harsh (2011). Encyclopedia of Solid Earth Geophysics. Springer Science & Business Media. p. 128. ISBN 978-90-481-8701-0.
• McCarthy, Dennis D.; Seidelmann, Kenneth P. (2009). Time: From Earth Rotation to Atomic Physics. Wiley. p. 290. ISBN 978-3-527-62795-0.

External links

• Official website
• (in English, French, and Russian) Earth Orientation Center of the IERS : data and interactive analysis (Paris Observatory)
• (in English and French) IERS International Celestial Reference Frame center

v t e Time measurement and standards
Chronometry Orders of magnitude Metrology
International standards	Coordinated Universal Time offset UT ΔT DUT1 International Earth Rotation and Reference Systems Service ISO 31-1 ISO 8601 International Atomic Time 12-hour clock 24-hour clock Barycentric Coordinate Time Barycentric Dynamical Time Civil time Daylight saving time Geocentric Coordinate Time International Date Line IERS Reference Meridian Leap second Solar time Terrestrial Time Time zone 180th meridian
Obsolete standards	Ephemeris time Greenwich Mean Time Prime meridian
Time in physics	Absolute space and time Spacetime Chronon Continuous signal Coordinate time Cosmological decade Discrete time and continuous time Proper time Theory of relativity Time dilation Gravitational time dilation Time domain Time-translation symmetry T-symmetry
Horology	Clock Astrarium Atomic clock Complication History of timekeeping devices Hourglass Marine chronometer Marine sandglass Radio clock Watch stopwatch Water clock Sundial Dialing scales Equation of time History of sundials Sundial markup schema
Calendar	Gregorian Hebrew Hindu Holocene Islamic (lunar Hijri) Julian Solar Hijri Astronomical Dominical letter Epact Equinox Intercalation Julian day Leap year Lunar Lunisolar Solar Solstice Tropical year Weekday determination Weekday names
Archaeology and geology	Chronological dating Geologic time scale International Commission on Stratigraphy
Astronomical chronology	Galactic year Nuclear timescale Precession Sidereal time
Other units of time	Instant Flick Shake Jiffy Second Minute Moment Hour Day Week Fortnight Month Year Olympiad Lustrum Decade Century Saeculum Millennium
Related topics	Chronology Duration music Mental chronometry Decimal time Metric time System time Time metrology Time value of money Timekeeper

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