8 Summary

1.

We present for the first time the full set of Lick indices for a sample of metal-rich globular clusters in the Galactic bulge.

2.

The Mg₂ and $\langle$Fe$\rangle$ indices of the most metal-rich globular clusters (NGC 5927, NGC 6528, and NGC 6553) are similar to those of the bulge, indicating that cluster and bulge fields have a similar [Fe/H] ratio.

3.

The CN index is clearly stronger in metal-rich globular clusters, compared to the stellar population in the Galactic bulge.

4.

All the metallicity-sensitive indices are tightly correlated with the $\langle$Fe$\rangle$ index (Spearman rank coefficient $\geq$0.87).

5.

We provide empirical calibrations of several indices versus [Fe/H] in the range $-2.29\leq\rm [Fe/H]\leq-0.17$. We find that the Mg₂ and the [MgFe] index are the best metallicity indicators with a rms of 0.15 dex.

6.

The H$\beta$ index shows a large scatter as a function of galactocentric distance which can be explained by the changing horizontal branch morphology.

7.

All other indices decrease with galactocentric radius and have constant low values beyond the radius of $\sim$10 kpc.

Acknowledgements

We acknowledge the use of the Lick standard star database which is maintained by Guy Worthey. THP gratefully acknowledges the support of the German Deutsche Forschungsgemeinschaft, DFG under the project number Be 1091/10-1. We would like to thank the anonymous referee for a careful and constructive report.