Gaussian fit to the emission lines after subtraction of the three different continua (Cont25, Cont50, Cont75) from the spectrum of AGNc1, smoothed by a 1D Gaussian kernel with σ = 3 pixels. The vertical dotted brown line indicates the expected wavelength λ_sys of the respective emission line, highlighting that the redshift determined from the peak of the C III]λ1908 line complex could be overestimated and the He II λ1640 line might be misidentified. Blue spectral regions mark the 50 Å windows used to calculate the continuum.