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We present a method for determining mean light-weighted ages and abundancesof Fe, Mg, C, N, and Ca, from medium resolution spectroscopy of unresolvedstellar populations. The method, pioneered by Schiavon (2007), is implementedin a publicly available code called EZ_Ages. The method and error estimationare described, and the results tested for accuracy and consistency, byapplication to integrated spectra of well-known Galactic globular and openclusters. Ages and abundances from integrated light analysis agree with studiesof resolved stars to within +/-0.1 dex for most clusters, and to within +/-0.2dex for nearly all cases. The results are robust to the choice of Lick indicesused in the fitting to within +/-0.1 dex, except for a few systematicdeviations which are clearly categorized. The realism of our error estimates ischecked through comparison with detailed Monte Carlo simulations. Finally, weapply EZ_Ages to the sample of galaxies presented in Thomas et al. (2005) andcompare our derived values of age, [Fe/H], and [alpha/Fe] to their analysis. Wefind that [alpha/Fe] is very consistent between the two analyses, that ages areconsistent for old (Age > 10 Gyr) populations, but show modest systematicdifferences at younger ages, and that [Fe/H] is fairly consistent, with smallsystematic differences related to the age systematics. Overall, EZ_Agesprovides accurate estimates of fundamental parameters from medium resolutionspectra of unresolved stellar populations in the old and intermediate-ageregime, for the first time allowing quantitative estimates of the abundances ofC, N, and Ca in these unresolved systems. The EZ_Ages code can be downloaded athttp://www.ucolick.org/~graves/EZ_Ages.html

Measuring Ages and Elemental Abundances from Unresolved Stellar Populations: Fe, Mg, C, N, and Ca