When they are established with sufficient precision, the ages, metallicities and kinematics of Galactic globular clusters (GGCs) can shed much light on the dynamical and chemical evolution of the Galactic halo and bulge. While the most fundamental way of determining GC abundances is by mean high-resolution spectroscopy, in practice this method is limited to only the brighter stars in the nearest and less reddened objects. This restriction has, over the years, led to the development of a large number of techniques that measure the overall abundance indirectly from parameters that correlate with overall metallicity. One of the most efficient methods is measuring of the equivalent width (EW) of the calcium II triplet (CaT) at {lambda}~~8500{AA} in red giants, which are corrected for the luminosity and temperature effects using the V magnitude differences from the horizontal branch (HB). We establish a similar method in the near-infrared (NIR), by combining the power of the differential magnitudes technique with the advantages of NIR photometry to minimize differential reddening effects. We used the Ks magnitude difference between the star and the reddest part of the HB (RHB) or of the red clump (RC) to generate reduced equivalent widths (rEW) from the previously presented datasets. Then we calibrated these rEW against three previously reported different metallicity scales; one of which we corrected using high-resolution spectroscopic metallicities.

Cone search capability for table J/A+A/563/A76/table1 (List of reddest parts of the Horizontal Branch (RHB) levels in the 30 glubular clusters)

Cone search capability for table J/A+A/563/A76/table8 (Equivalent widths of the Ca-II triplet ({lambda}~850nm))