Step-by-step of the member star selection for NGC 6528. The black dots are selected member stars, grey dots are non-members, and green circles show stars considered as cluster member by Saviane et al. (2012), but non-members in the present work. The blue solid lines are drawn based on values of Table 2, which were also applied to the ischrones from Dotter et al. (2008). For isochrones we use age, [Fe/H] and [α/Fe] information. The red dashed lines refer to the weighted average of the member star parameters.