Towards sub-microarcsecond models for relativistic astrometry

TL;DR

This paper reviews the current state of relativistic astrometry, focusing on light propagation modeling for high-precision space missions like Gaia, and discusses ongoing research challenges.

Contribution

It provides a comprehensive overview of the current models and identifies key problems in light-ray equations and metric formulation for microarcsecond accuracy.

Findings

Current models aim for accuracies below a microarcsecond

Challenges remain in formulating the BCRS metric

Ongoing research addresses light-ray equation solutions

Abstract

Astrometric space missions like Gaia have stimulated a rapid advance in the field of relativistic astrometry. Present investigations in that field aim at accuracies significantly less than a microarcsecond. We review the present status of relativistic astrometry. As far as the problem of light propagation is concerned we face two problems: the form of the BCRS metric and solutions to the light-ray equation. Finally, work in progress in that field is briefly mentioned.