Deuteration maps of H₂CS towards L1544. The column density ratio has been computed only in pixels where both molecules have been observed at least at a 3σ level. The solid white contours are the 30%, 60%, and 90% of the peak intensity of the N(H₂) map of L1544 computed from Herschel/SPIRE data. The dotted white contours indicate the 3σ integrated emission contour for HDCS in the left panel, and of D₂CS in the central and right panel.