Ages of Galactic Globular Clusters from the New Yale Isochrones

A new grid of theoretical isochrones based on the Yale stellar evolution code using the OPAL and Kurucz opacities has been constructed. The grid of isochrones spans a wide range of metallicities, helium abundances and masses. The construction of the isochrones is described and the isochrones are compared to galactic globular cluster observations. A solar calibrated mixing length ($\alpha = 1.7$) yields a good fit to globular cluster colour-magnitude diagrams. Ages for 40 globular clusters are determined using the \dv method and the formation of the halo is discussed.