We describe a long term project aimed at deriving information on the chemicalevolution of the Galactic disk from a large sample of open clusters. The mainproperty of this project is that all clusters are analyzed in a homogeneousway, to guarantee the robustness of the ranking in age, distance andmetallicity. Special emphasis is devoted to the evolution of the earliestphases of the Galactic disk evolution, where clusters have superior reliabilitywith respect to other types of evolution indicators. The project is twofold: onthe one hand we derive age, distance and reddening (and indicative metallicity)interpreting deep and accurate photometric data with stellar evolution models,and, on the other hand, we derive the chemical abundances from high-resolutionspectroscopy. Here we describe our overall goals and approaches, and report onthe mid-term project status of the photometric part, with 16 clusters alreadystudied, covering an age interval from 0.1 to 6 Gyr and Galactocentricdistances from 6.6 to 21 kpc. The importance of quantifying the theoreticaluncertainties by deriving the cluster parameters with various sets of stellarmodels is emphasized. Stellar evolution models assuming overshooting fromconvective regions appear to better reproduce the photometric properties of thecluster stars. The examined clusters show a clear metallicity dependence on theGalactocentric distance and no dependence on age. The tight relation betweencluster age and magnitude difference between the main sequence turn off and thered clump is confirmed.
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