A novel approach for direct estimation of the instantaneous Earth rotation velocity

• Autores: Titov, O.
• Año de publicación: 2025
• Idioma: inglés
• Tipo de recurso: documento de conferencia
• Materia: Ciencias Astronómicas; Fringe frequency; Earth rotation velocity; VLBI observables
• Institución: Universidad Nacional de La Plata

Very Long Baseline Interferometry (VLBI) measures two standard observables: group delay and fringe frequency (delay rate). While the group delay is widely used to estimate a large set of geodetic and astrometric parameters, the fringe frequency has been largely ignored to date. However, the fringe frequency is a unique tool for direct estimation of the instantaneous Earth angular rotation velocity which is not accessible with the group delay alone. This study aims to estimate the magnitude of the Earth angular rotation velocity and, in addition, daily estimates of X and Y angles (celestial pole offset) linking the Celestial Instantaneous Pole (CIP) and the International Celestial Reference System (ICRS) pole. Least squares method is applied for analysis of the fringe frequency from the routine geodetic VLBI observations since 1993 (IVS-R1, R4 programs). Three components of the Earth rotation vector are estimated with a formal error of 1 prad/s or 10-8 in relative units, or even better, if a large international VLBI network is at work. Using the newly obtained values one could 1) monitor the Earth rotation irregularity in parallel to the traditional length-of-day (LCD) values; and 2) assess the modern precession-nutation theory directly.
Facultad de Ciencias Astronómicas y Geofísicas