Line luminosities of APM 08279+5255 and NCv1.143 (based on the line fluxes listed in Table 5, where we also include several detections from the literature). Error bars are propagated from the measured flux errors. The upper panel shows the line luminosity in K km s⁻¹ pc², , normalized by the value of C¹⁸O(4–3). The lower panel shows the line luminosity in L_⊙, L_line, normalized by the C¹⁸O(4–3) line. The lowest levels of the transitions of each molecule detected are labeled at the top of each panel, except for H₂O and H₃O⁺, where the rest-frame frequencies in GHz are given. Each transition is identified in the upper part of the figure. Compared with NCv1.143, the excitation condition is more extreme in APM 08279+5255 as seen from the SLEDs from several molecules.