Non-detection of significant signal from C IV emission within LAB 1. Left panel: maximum S/N after cross-correlation with a 3D Gaussian template (see Sect. 5.2). Here the S/N cube was evaluated between λ_min = 6345 Å and λ_max = 6360 Å. Right panels: spectral extractions in the regions “south”, “north”, and “LAB 8”, where significant He II emission was detected (Fig. 10). In each of those panels, the black curve shows the extracted spectrum, while the grey curve shows the propagated noise from the variance datacube. Vertical dotted lines indicate the rest-frame wavelengths of the C IV doublet. We also show a smoothed version (Gaussian window, σ = 3 px) of the spectrum (blue curve), which suppresses the high-frequency and high-amplitude oscillations from systematic sky-subtraction residuals in this wavelength range.