Numerical Data-Processing Simulations of Microarcsecond Classical and Relativistic Effects in Space Astrometry

TL;DR

This paper presents a comprehensive relativistic model and software for processing high-precision space astrometry data, accounting for classical and relativistic effects to achieve microarcsecond accuracy.

Contribution

It develops a detailed relativistic data-processing software for space interferometry, including effects like light deflection and aberration, for microarcsecond precision.

Findings

Software accurately models relativistic light deflection effects.

Numerical simulations demonstrate disentangling of classical and relativistic effects.

Achieves microarcsecond-level astrometric measurement accuracy.

Abstract

The accuracy of astrometric observations conducted via a space-borne optical interferometer orbiting the Earth is expected to approach a few microarcseconds. Data processing of such extremely high-precision measurements requires access to a rigorous relativistic model of light ray propagation developed in the framework of General Relativity. The data-processing of the space interferometric observations must rely upon the theory of general-relativistic transformations between the spacecraft, geocentric, and solar barycentric reference systems allowing unique and unambiguous interpretation of the stellar aberration and parallax effects. On the other hand, the algorithm must also include physically adequate treatment of the relativistic effect of light deflection caused by the spherically-symmetric (monopole-dependent) part of the gravitational field of the Sun and planets as well as the quadrupole- and spin-dependent counterparts of it. In some particular cases the gravitomagnetic field induced by the translational motion of the Sun and planets should be also taken into account for unambigious prediction of the light-ray deflection angle. In the present paper we describe the corresponding software program for taking into account all classical (proper motion, parallax, etc.) and relativistic (aberration, deflection of light) effects up to the microarcsecond threshold and demonstrate, using numerical simulations, how observations of stars and/or quasars conducted on board a space optical interferometer orbiting the Earth can be processed and disentangled.