Example for the intrinsic mapping of the Lyα nebula of TNJ0205+2242. The central panel shows the intrinsic surface brightness map of TNJ0205+2242 which is the same as Fig. 1b. The green cross and triangles mark the position of the AGN and jet lobes, respectively. In each of the side panel, we show the spectrum (blue shade histogram in normalised flux unit) extracted from the individual spatial bin whose number is labelled at the top left, and the best fit (dark magenta curve) and recovered intrinsic Lyα (dashed red line). The black vertical bars indicate the positions of the H I absorbers.