IERS

The International Earth Rotation and Reference Systems Service (IERS) is an international service that coordinates the collection, interpretation, and dissemination of data related to the Earth's rotation and the reference systems used to describe positions on and near its surface. It operates under the auspices of the International Astronomical Union (IAU) and the International Union of Geodesy and Geophysics (IUGG), and encompasses a global network of observatories and analysis centers.

IERS monitors the Earth's rotation and orientation, including UT1, polar motion, and precession, and provides realizations of the International Terrestrial Reference System (ITRS) and its connections to the International Celestial Reference System (ICRS). It also coordinates timekeeping by tracking the relationship between UT1 and UTC and issuing announcements related to leap seconds, which align atomic time with solar time.

Data products include Earth Orientation Parameters (EOPs) in rapid and final forms, such as polar motion (xp, yp), UT1 − UTC (DUT1), and the length of day; daily and periodic bulletins (Bulletins A, B, and C); and the IERS Conventions document. The IERS relies on observations from very-long-baseline interferometry (VLBI), satellite laser ranging (SLR), GPS, and DORIS networks to produce these standards.

Administration and history: The IERS was established in 1988 as a joint service of the IAU and IUGG to coordinate Earth orientation and reference-frame work. It is organized through an international collaboration of institutions, with the Observatoire de Paris traditionally playing a leading role.

Impact and applications: IERS data underpin precise astronomical observations, spacecraft navigation and tracking, satellite orbit determination, geodesy, and global timekeeping. They are essential for maintaining the ITRF and linking terrestrial and celestial reference frames.

Access and governance: IERS data and publications are publicly available through the IERS website. The IERS Conventions document provides the formal description of the reference frames and algorithms used in analysis.