Left panel: CMD of the synthetic stars from the BASTI model shown in Fig. 4 having 25.5 ≤ F606W ≤ 28.0. The meaning of the symbols is the same as in Fig. 4. The continuous line is the corresponding Zero Age HB model, plotted in both panels as a reference. Right panel: simulation of the observation process on the synthetic stars, obtained from the artificial stars experiments (sample with r_ϵ > 1.5′). Note that the output HB morphology is very similar to the observed one.