Observing strategy - introduction

The Gaia-ESO Survey observing strategy has been designed to deliver the top-level survey goal. We will survey the Galactic inner and outer bulge, inner and outer thick and thin discs, the halo and known halo streams. We have particular focus on the local thin disc, as this study both complements Gaia astrometry, and will benefit most from the most precise Gaia data. We place special effort on open clusters at all ages and the solar neighbourhood field stars as tracers of both stellar and Galactic evolution.

The Fibre Large Array Multi Element Spectrograph (FLAMES) instrument will be used to obtain the spectra. Observations are restricted to +10 ≥ dec ≥−60 whenever possible to minimise airmass limits. The primary source catalog for field stars is VISTA imaging, ensuring excellent recent astrometry, and adding maximal value to the VISTA surveys. The open clusters have been selected from the Dias et al. (2002, A&A 389, 871 - 2010 version) and Kharchenko et al. (2005, A&A 440, 403) catalogues, and WEBDA database and the results of a monitoring programme carried out by the Geneva group. Only clusters with available photometry and membership information have been selected.