Spectral energy distribution (SED) of the compact quasar (J2339−5523) and its flat-spectrum core component. Left panel: SED of J2339−5523 obtained by combining measurements from GLEAM (red circles), the MALS L- and UHF-bands (blue circles), SUMSS (brown plus), and the AT20G catalog (magenta circles). A power-law (S_ν ∝ ν^α) fit (dashed black line) to the MALS and GLEAM flux densities yields a spectral index, α = −0.71 ± 0.01. The dotted lines represent the SED attenuated by FFA due to a range of emission measures. Right panel: attenuation of the flat-spectrum core component due to FFA for a range of emission measures. In both panels, asterisks represent ν_p (see Sect. 3.3).