Light Deflection for relativistic space astrometry in closed form

TL;DR

This paper introduces a closed-form relativistic model for light deflection in space astrometry, leveraging time transfer functions to simplify photon trajectory calculations for high-precision observations.

Contribution

It presents a novel closed-form solution for light deflection in relativistic space astrometry using time transfer functions, avoiding explicit null geodesic solutions.

Findings

Provides a closed-form expression for light deflection

Enhances the accuracy of relativistic astrometric modeling

Simplifies calculations for future high-precision space missions

Abstract

Given the extreme accuracy reached by future global space astrometry, one needs a global relativistic modeling of observations. A relativistic definition of astrometric observables is then essential to find uniquely coordinates, parallax and proper motion of a stellar object. The standard procedure is to explicitly solve the null geodesic equations to describe the trajectory of a photon emitted by a celestial object and received by a moving observing satellite. However, this task can be avoided if one builds an astrometric set up using the recent formalism of time transfer functions.