Deuterium fraction map of methanol using the column density maps of CH₂ DOH and CH₃OH derived as described in Sect. 4.1. The black contours represent increasing 10% steps of the peak of the Herschel N(H₂) map, presented by Spezzano et al. (2016). The beams are shown in the bottom right corner of the figure, in yellow for Herschel/SPIRE and in white for the 30 m telescope. The black cross marks the dust continuum peak, and only values above the 3σ detection level are considered.