A test field for Gaia. Radial velocity catalogue of stars in the South Ecliptic Pole

TL;DR

This paper presents a ground-based spectroscopic survey of stars in the South Ecliptic Pole to validate Gaia's radial velocity measurements, providing a valuable dataset for calibration and performance assessment.

Contribution

It offers the first radial velocity catalogue for stars in the South Ecliptic Pole, aiding Gaia's validation process and improving its data accuracy.

Findings

Radial velocities measured for stars in the 12-17 magnitude range.

Spectroscopic data obtained with GIRAFFE and UVES instruments.

Dataset supports Gaia's radial velocity calibration efforts.

Abstract

Gaia is a space mission currently measuring the five astrometric parameters as well as spectrophotometry of at least 1 billion stars to G = 20.7 mag with unprecedented precision. The sixth parameter in phase space (radial velocity) is also measured thanks to medium-resolution spectroscopy being obtained for the 150 million brightest stars. During the commissioning phase, two fields, one around each ecliptic pole, have been repeatedly observed to assess and to improve the overall satellite performances as well as the associated reduction and analysis software. A ground-based photometric and spectroscopic survey was therefore initiated in 2007, and is still running in order to gather as much information as possible about the stars in these fields. This work is of particular interest to the validation of the Radial Velocity Spectrometer (RVS) outputs. The paper presents the radial velocity measurements performed for the Southern targets in the 12 - 17 R magnitude range on high- to mid-resolution spectra obtained with the GIRAFFE and UVES spectrographs.