Earth rotation and reference frames

• Autores: Schuh, H.; Heinkelman, R.
• Año de publicación: 2025
• Idioma: inglés
• Tipo de recurso: documento de conferencia
• Materia: Ciencias Astronómicas; Earth Orientation Parameters (EOP); Space geodetic techniques; Very Long Baseline Interferometry (VLBI)
• Institución: Universidad Nacional de La Plata

Since the late 1970s, space geodetic techniques have been used to measure Earth orientation parameters (EOP). VLBI (Very Long Baseline Interferometry) is the only method capable of observing all five EOP in terms of polar motion, UT1-UTC, and celestial pole offsets without external information. The EOP link the station coordinates given in the ITRF (International Terrestrial Reference Frame) to the sky-fixed system of extragalactic radio sources, the ICRF (International Celestial Reference Frame), which is typically implemented using VLBI observations of AGN (Active Galactic Nuclei). All satellite techniques, such as SLR (Satellite Laser Ranging), GNSS (Global Navigation Satellite Systems) and DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite) are suitable for highly accurate measurements of pole coordinates and length-of-day (lod) that corresponds to the temporal rate of UT1-UTC. Today, EOP are determined using combined solutions of the above-mentioned space geodetic techniques, with various approaches possible: combining the results of the individual techniques, combination at the normal equation level, or combination at the observation equation level. The operational results of EOP can be compared with more recently developed and established methods such as LLR (Lunar Laser Ranging) and ring laser measurements. The latter use a completely different concept: instead of being connected to targets outside of the solid Earth, as with VLBI and satellite techniques, local sensors are used to measure the Earth's variable rotation rate via laser beam and the Sagnac effect. New developments in Earth rotation observation will be presented such as current ring laser observations and future satellite missions as for instance the ESA satellite GENESIS, which will enable the co-location of the main four space geodetic techniques (VLBI, SLR, GNSS, DORIS) in space. This will be complemented by simulations of satellite constellations and network configurations.
Facultad de Ciencias Astronómicas y Geofísicas