Horsehead per pixel maps of the aliphatic (3.4 μm) and aromatic (3.3 μm) integrated band strength. Middle panel: aromatic in blue, aliphatic in red. Bottom panel: ratio of aliphatic to aromatic band strengths. Top panel: cuts along the long mosaic axis. Aromatic and aliphatic cuts are in blue and red, respectively (as for the middle panel), and the band ratio is plotted in black; see the y-axis on the right.