Identified long-period variables in the N_8.6   μm, (V_° − N_8.6   μm) plane. Certain identifications of the LPVs are plotted as red open circles, while uncertain identifications are plotted in different symbols, and only for the most plausible candidates. The V magnitudes of the LPVs were corrected for the known variability cycle, i.e. shifted to their average luminosity. The RGB tip is at N_8.6   μm ≃ 7.0, while the suggested luminosity break is at N_8.6   μm ≃ 8.0, corresponding to  ~ 1000   L_⊙.