One-dimensional spectral extractions centred on the north-western (top) and south-eastern (bottom) part of ID53, focussing on the C IV_1548, 1550 doublet. The extraction is based on HST/ACS morphology (Fig. 3) using the ODHIN software. The dashed red line shows the continuum level from the best-fit stellar population model (see Sect. 4). Spectra are normalised to this continuum level. Vertical dashed lines mark the expected position of the C IV doublet at the systemic redshift.