The deflection of light induced by the Sun's gravitational field and measured with geodetic VLBI
The Sun's gravitational field deflects the apparent positions of close objects in accordance with the formulae of general relativity. Optical astrometry is used to test the prediction, but only with the stars close to the Sun and only during total Solar eclipses. Geodetic Very Long Baseline Interferometry (VLBI) is capable of measuring the deflection of the light from distant radio sources anytime and across the whole sky. We show that the effect of light deflection is equivalent to the gravitational delay calculated during the reduction of VLBI data. All reference radio sources display an annual circular motion with the magnitude proportional to their ecliptic latitude. In particular, radio sources near the ecliptic pole draw an annual circle with magnitude of 4~mas. This effect could be easily measured with the current precision of the geodetic VLBI data.
Journées 2014 "Systèmes de référence spatio-temporels"
- Pub Date:
- August 2015
- Earth rotation;
- reference systems;
- General Relativity and Quantum Cosmology;
- Astrophysics - Instrumentation and Methods for Astrophysics
- Proc. of "Journees-2014" meeting (edited by Z. Malkin and N. Capitaine), pp. 75-78