Phoebe's orbit from ground-based and space-based observations

TL;DR

This paper improves Phoebe's orbital ephemeris using a comprehensive set of ground-based and space-based observations, correcting systematic errors, and updating the dynamical model, achieving high accuracy in Phoebe's predicted position.

Contribution

It introduces an enhanced dynamical model and a refined observational dataset to produce a more accurate ephemeris for Phoebe, surpassing previous models.

Findings

Residuals of 0.45 arcsec in ephemeris predictions

Estimated positional accuracy of less than 100 km (1990-2020)

Improved consistency with recent planetary and satellite ephemerides

Abstract

The ephemeris of Phoebe, the ninth satellite of Saturn, is not very accurate. Previous dynamical models were usually too simplified, the astrometry is heterogeneous and, the Saturn's ephemeris itself is an additionnal source of error. The aim is to improve Phoebe's ephemeris by using a large set of observations, correcting some systematic errors and updating the dynamical model. The dynamical model makes use of the most recent ephemeris of planets and Saturnian satellites. The astrometry of Phoebe is improved by using a compilation of ground-based and space-based observations and by correcting the bias in stellar catalogues used for the reduction. We present an accurate ephemeris of Phoebe with residuals of 0.45 arcsec and with an estimated accuracy of Phoebe's position of less that 100 km on 1990-2020 period.