2D completeness function (C_2D(M, μ_e)) for the Coma field and the reference fields (top) and its relative uncertainty (bottom). The dashed red line indicates ﹩M=-11.3\,{g}^{{\prime} }\,{\rm{mag}}﹩, the limiting magnitude adopted for the GLF analysis. At this magnitude, the corresponding 1D completeness of the Coma cluster is approximately 20%. Overlayed in black are the individual quiescent galaxies, detected in the individual fields. Absolute magnitudes are expressed on a Coma-equivalent scale, used as a common reference scale rather than a physical distance assumption.