VLT/X-shooter spectra at various epochs, plotted in velocity space for He II (black) and Hα (orange). To guide the eye, we show: the rest velocity as a solid line; the photospheric velocity with a vertical dashed line, which happens to coincide with the expected position for N IIIλ4640; and the position for Hβ with respect to He II as a black dotted line. For display purposes, narrow emission lines have been removed and the spectra are resampled to lower spectral resolution.