Observed spectra (in blue) around the HO₂ transition at 236.280920 GHz (left panel) and around the H₂O₂ transition at 235.955943 GHz (right panel), respectively, towards the western half beam position. The red line in the left and right panels shows the modelled spectrum at LTE obtained with a HO₂ column density of 1.1 × 10¹⁴ cm⁻² and T_ex = 125 K and a c-C₂H₄O column density of 6.1 × 10¹⁵ cm⁻² and T_ex = 125 K, respectively (see text). Positions in arcsec relative to the continuum peak position of IRAS 16293 B are shown at the top left of each panel. The vertical and horizontal black dashed lines depict the source velocity at 2.7 km s⁻¹ and the baseline, respectively.