Validation of the new Hipparcos reduction

TL;DR

This paper validates the improved accuracy and reduced error correlations of the new Hipparcos astrometric catalogue, confirming its enhanced precision over the previous version and its suitability for stellar and galactic studies.

Contribution

The paper provides a thorough validation of the new Hipparcos reduction, confirming improved accuracy and error characteristics compared to the original catalogue.

Findings

Formal errors on parallaxes are confirmed.

Error correlations are significantly reduced, explaining the improvement.

The new catalogue has 2.2 times more weight than the 1997 version.

Abstract

Context.A new reduction of the astrometric data as produced by the Hipparcos mission has been published, claiming accuracies for nearly all stars brighter than magnitude Hp = 8 to be better, by up to a factor 4, than in the original catalogue. Aims.The new Hipparcos astrometric catalogue is checked for the quality of the data and the consistency of the formal errors as well as the possible presence of error correlations. The differences with the earlier publication are explained. Methods. The internal errors are followed through the reduction process, and the external errors are investigated on the basis of a comparison with radio observations of a small selection of stars, and the distribution of negative parallaxes. Error correlation levels are investigated and the reduction by more than a factor 10 as obtained in the new catalogue is explained. Results.The formal errors on the parallaxes for the new catalogue are confirmed. The presence of a small amount of additional noise, though unlikely, cannot be ruled out. Conclusions. The new reduction of the Hipparcos astrometric data provides an improvement by a factor 2.2 in the total weight compared to the catalogue published in 1997, and provides much improved data for a wide range of studies on stellar luminosities and local galactic kinematics.