Correlated and zonal errors of global astrometric missions: a spherical harmonic solution

TL;DR

This paper introduces a computationally efficient spherical harmonic method to estimate spatially correlated errors in astrometric data, applicable to various space missions, improving error analysis accuracy.

Contribution

The paper presents a novel spherical harmonic-based approach for estimating correlated astrometric errors, enhancing accuracy and efficiency over traditional methods.

Findings

Effective estimation of correlated errors demonstrated on JMAPS data

Method applicable to multiple space astrometry missions

Improves accuracy of error characterization in astrometric catalogs

Abstract

We propose a computer-efficient and accurate method of estimation of spatially correlated errors in astrometric positions, parallaxes and proper motions obtained by space and ground-based astrometry missions. In our method, the simulated observational equations are set up and solved for the coefficients of scalar and vector spherical harmonics representing the output errors, rather than for individual objects in the output catalog. Both accidental and systematic correlated errors of astrometric parameters can be accurately estimated. The method is demonstrated on the example of the JMAPS mission, but can be used for other projects of space astrometry, such as SIM or JASMINE.