IR-optical-UV SED of B2 1023+25. The solid black line shows the SDSS spectrum, with the clearly visible Lyα clouds absorption at Log ν > 15.4. Dark green circles are WISE data, and light green squares are GROND data (Sbarrato et al. 2013a). The red line shows the best accretion disc fitting, while the grey stripe shows the range outside of which the modelling cannot be considered valid, all performed with the Kubota & Done (2019) model with parameters as labelled. The best fit is used to locate the peak of the emission and derive the KERRBB-based mass and spin estimates.