M 67

The open cluster M 67 has an age of $\sim$ 3.5 $^{+1.0}_{-0.5}$ Gyr and nearly solar metallicity ([Fe/H] = 0.0 $\pm$ 0.1). Therefore, it inhabits a region of parameter space that is very important for studies of the integrated light of galaxies, both nearby and at large distances, where early-type galaxies are often found to have similar mean ages and metallicities (e.g., Trager et al. 2000, Kelson et al. 2001, Caldwell et al. 2003, Denicoló et al. 2005a,b, Gallazzi et al. 2005, Schiavon et al. 2006).