Radial profiles of the star formation efficiency (upper panel) and the H₂-to-H I surface density ratio (bottom panel). The SFE is defined here as the star formation rate per unit of molecular gas. The blue squares correspond to the 17 pointings used to map CO along the M 63 major axis (the radial cut) out to the isophotal radius, r₂₅ (dashed line), and the red circles correspond to the 8 pointings with 24 μm emission detection used to map CO over the bright UV region at r_gal = 1.36 r₂₅. The double data points plotted for the UV region at each r_gal correspond to the parallel pointings used to map this region (see Table 2).