Auroral emission lines detected in the MARTA golden sample. The panels show emission line fits of the [S II] λ4068,4076, [O III] λ4363, [S III] λ6312, and [O II] λ7320,7330 transitions, with their rest-frame wavelengths marked as dashed blue lines. We show the continuum-subtracted spectra in black, and the Gaussian emission-line fits in blue. In the case of [S III] λ6312, two single Gaussians are shown (dashed red lines), since the [S III] line is blended with the [O II] λ6300.