Three X-shooter spectra (MJD = 55452.89, 55585.65, 56708.04, see legend) corresponding to phases close to the RV extremes (ϕ = 0.05, 0.84 with ephemeris derived in this study) and the systemic velocity (ϕ = 0.96) of the N IV λ4058 and N V λ4945 lines. Both binary components are seen in the N IVλ4058 line, but only the hotter primary is seen in the N Vλ4945 line. Conversion to Doppler space is with reference to rest wavelengths.