NICS spectrum of APM 08279+5255 corresponding to the Mg II and Hβ+[O III] spectral regions. Specifically, panel a shows the best fit description of the restframe ~ 2200−3400 Å band. Panel b and its inset show the best-fit description of the restframe ~ 3990−5040 Å band according to models A and B, respectively. In all panels, a purple solid line marks the power-law quasar continuum. Blue dashed curves refer to Mg II, Hγ, and Hβ emission lines, whereas the Fe II emission is plotted as magenta dot-dashed lines. In model B, the green curve refers to the [O III] emission. Gray bands indicate the regions excluded from the fit because of the presence of telluric features.