Example PPXF fits for two GCs for which we measure velocity dispersions (top GC73, bottom GC39). The FLAMES GIRAFFE spectra are shown in black, the optimal model template in orange and residuals of the fit are shown underneath in blue. The greyed out areas are regions of strong sky residuals which are masked out in the fitting procedure. The zoom-in regions are centred around the three lines of the calcium triplet. The first line of the calcium triplet (at ∼ 8549 Å) is strongly affected by a sky residual. Fits to all the spectra are shown in Fig. A.1.