Top panel: SED of the quasar J1342 in the rest frame whose observed disk luminosity is erg s⁻¹. Photometric data (red points) and spectrum (black line) are from Bañados et al. (2018, see this work for details regarding these data). Central panel: SED of the quasar J1120 in the rest frame with an observed disk luminosity erg s⁻¹. Photometric data (red points) and spectrum (black line) are from the work by Mortlock et al. (2011). Bottom panel: SED of the quasar J0038 in the rest frame with an observed disk luminosity erg s⁻¹. Photometric data (red points) and spectrum (black line) are from the work by Wang et al. (2018). In these panels the blue curve is the “best fit” obtained using the relativistic model KERRBB. The red curves describe the confidence interval for the spectrum peak frequency and luminosity from the model. The vertical orange line indicates the Lyα line frequency: at frequencies larger than this latter, data are strongly affected by intervening Lyα clouds along our line of sight and therefore we did not include these data in our fit.