Spectroscopic completeness for sources with a photometric redshift z< 0.3 as a function of stellar mass (assuming the same distance modulus as the cluster redshift). The four lines show different radial bins. For targets of a given stellar mass, the spectroscopic completeness is slightly higher for those that are closer to the cluster centres. For each of the radial bins, the completeness is larger than 70% for stellar masses M_⋆> 10¹¹M_⊙.