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We present wide field near-infrared photometry of 12 Galactic globularclusters, typically extending from the tip of the cluster red giant branch(RGB) to the main sequence turnoff. Using recent homogenous values of clusterdistance, reddening and metallicity, the resulting photometry is directlycompared to the predictions of several recent libraries of stellar evolutionarymodels. Of the sets of models investigated, Dartmouth and Victoria-Reginamodels best reproduce the observed RGB morphology, albeit with offsets in J-Kscolor which vary in their significance in light of all sources of observationaluncertainty. Therefore, we also present newly recalibrated relations betweennear-IR photometric indices describing the upper RGB versus cluster ironabundance as well as global metallicity. The influence of enhancements in alphaelements and helium are analyzed, finding that the former affect the morphologyof the upper RGB in accord with model predictions. Meanwhile, the empiricalrelations we derive are in good agreement with previous results, and minordiscrepancies can likely be attributed to differences in the assumed clusterdistances and reddenings. In addition, we present measurements of thehorizontal branch (HB) and RGB bump magnitudes, finding a non-negligibledependence of the near-IR HB magnitude on cluster metallicity. Lastly, wediscuss the influence of assumed cluster distances, reddenings andmetallicities on our results, finding that our empirical relations aregenerally insensitive to these factors to within their uncertainties.

Wide Field Near-Infrared Photometry of 12 Galactic Globular Clusters: Observations Versus Models on the Red Giant Branch