Maps for the O⁺⁺ (top left), O⁺, (top right), and O⁰ (bottom left) ionic abundances, derived using the direct method as described in the text. All the three maps display the same range in abundance in order to emphasise the relative contribution of each ion in the different parts of the galaxy. The last map in this figure (bottom right) contains the total oxygen abundance map, 12 + log(O/H). North is up and east towards the left.