Abundance indicators from vidicon spectra in six globular clusters

New spectrum measurements for six southern globular clusters are presented, and attention is given to the effectiveness of several parameters chosen from the spectra in establishing the metallicities of the clusters. The use of abundance indicators based on the variation of specific spectral features observed at approximately 3-4 A resolution is found to be effective in ranking globular cluster abundances. The use of relatively large samples of stars from each cluster, which deliberately cover the entire luminosity range along the giant branch, is an extremely helpful aspect of this type of approach to determine cluster abundances. It is found that the single parameter m(G), denoting the strength of the G band, relative to the immediately adjacent continuum, gives the clearest and most well defined separation between clusters. Three other selected line features are also sensitive to metallicity variations and in most cases gave highly consistent cluster rankings.