The OCCASO survey: Presentation and radial velocities of twelve Milky
  Way Open Clusters
  Open clusters (OCs) are crucial for studying the formation and evolution of
the Galactic disc. However, the lack of a large number of OCs analyzed
homogeneously hampers the investigations about chemical patterns and the
existence of Galactocentric radial and vertical gradients, or an
age-metallicity relation. To overcome this, we have designed the Open Cluster
Chemical Abundances from Spanish Observatories survey (OCCASO). We aim to
provide homogeneous radial velocities, physical parameters and individual
chemical abundances of six or more Red Clump stars for a sample of 25 old and
intermediate-age OCs visible from the Northern hemisphere. To do so, we use
high resolution spectroscopic facilities (R> 62,000) available at Spanish
observatories. We present the motivation, design and current status of the
survey, together with the first data release of radial velocities for 77 stars
in 12 OCs, which represents about 50% of the survey. We include clusters never
studied with high-resolution spectroscopy before (NGC~1907, NGC~6991,
NGC~7762), and clusters in common with other large spectroscopic surveys like
the Gaia-ESO Survey (NGC~6705) and APOGEE (NGC~2682 and NGC~6819). We perform
internal comparisons between instruments to evaluate and correct internal
systematics of the results, and compare our radial velocities with previous
determinations in the literature, when available. Finally, radial velocities
for each cluster are used to perform a preliminar kinematic study in relation
with the Galactic disc.
