Radio spectrum of SDSSJ08. The coloured markers present radio measurements from the literature. The empty triangle shows the TGSS-ADR1 upper limit which is not used for spectral fitting. At frequencies above ~ 1 GHz, the spectrum appears steep. The LOFAR 145 MHz (green and orange point) and the ASKAP 888 MHz (cyan and red point) flux densities reported in this work confirm a flattening of the spectrum at frequencies below ~ 1 GHz. The red and blue lines show the best-fitting spectra with the indices of − 0.30 ± 0.13 and − 1.02 ± 0.16 in the frequency ranges below and above 1.4 GHz, respectively. The best-fitting line for all data points with an index of − 0.62 ± 0.12 is shown with the grey dashed line.