Astrometric effect
Earth Orientation Parameters
The measured quantities that describe how the real, wobbling, irregularly rotating Earth is oriented in space relative to the celestial reference frame — the difference UT1−UTC, the position of the pole (polar motion), and small corrections to the precession-nutation model. Determined and published by the IERS, they are what make it possible to transform between celestial and terrestrial coordinates to full precision.
Highlights
- ›UT1−UTC, polar motion, and nutation offsets from the IERS
Related systems & concepts
Across the reference systems
Knowledge connections
- Associated withNutation
- Associated withInternational Earth Rotation and Reference Systems Service (IERS)
- Associated withUniversal Time (UT1)
- Associated withPrecession
- Associated withProper Motion
- Associated withInternational Earth Rotation and Reference Systems Service (IERS)
Sources
The primary and reference sources this topic draws on.
- IAUInternational Astronomical Union
Official naming, definitions, constellation boundaries, and astronomical nomenclature.