Continuum spectra of the variable, compact component in S255IR NIRS 3. The date of the observations is given in the top left of each panel. The vertical error bars assume a calibration error of 10% in all bands, while the horizontal bars indicate the bandwidth covered at each frequency. The upper limits denote that the flux density is also contributed by the emission from the large-scale lobes, due to the limited angular resolution. Red symbols mark data in the L (1.5 GHz) and S (3 GHz) bands. The curves are the best fits obtained with the model of a thermal jet described in Sect. 4.3.2.