He ii narrowband image magnified on the central region. The yellow contour is the 1.25 × 10^-15 erg s^-1 cm^-2 arcsec^-2 contour from the Hα image (Fig. 1, left). Colour scale in the inner high-SB region extends from 3 × 10^-18 to 3 × 10^-17erg s^-1 cm^-2 arcsec^-2, while for the outer region it is shown by the colour bar on the right. An asinh scaling is used. Contours correspond to [2.5,100,1000] × 10^-18 erg s^-1 cm^-2 arcsec^-2. The inset in the bottom left shows the emsission line free HST WFC3/F550M image from the galaxy within the region indicated by the red square.