Testing Intermediate-Age Stellar Evolution Models with VLT Photometry of Large Magellanic Cloud Clusters. I. The Data

This is the first of a series of three papers devoted to the calibration of afew parameters of crucial importance in the modeling of the evolution ofintermediate-mass stars, with special attention to the amount of convectivecore overshoot. To this end we acquired deep V and R photometry for threeglobular clusters of the Large Magellanic Cloud (LMC), namely NGC 2173, SL 556and NGC 2155, in the age interval 1-3 Gyr. In this first paper, we describe theaim of the project, the VLT observations and data reduction, and we makepreliminary comparisons of the color-magnitude diagrams with both Padova andYonsei-Yale isochrones. Two following papers in this series present the resultsof a detailed analysis of these data, independently carried out by members ofthe Yale and Padova stellar evolution groups. This allows us to compare bothsets of models and discuss their main differences, as well as the systematiceffects that they would have to the determination of the ages and metallicitiesof intermediate-age single stellar populations.Comment: 27 pages with 10 figures. Accepted by the Astronomical Journa