Top: zoom of the long-slit WHT spectrum around Hα (middle spectral line) and the [N ii] doublet. The wavelength increases from bottom to top. The slit was positioned at PA = 97°, and East is towards the left. The size of the box in the spatial direction is as in the bottom panel. Bottom: spatial profile of the [N ii]6583 line. The observed profile is indicated by the dotted line, the adjacent stellar continuum by the dashed line, and the continuum-subtracted [N ii] profile by the thick (red) solid line.