Integrated intensity maps of ¹³CO a), C¹⁸O b) and HCN c) emission lines of the G 333 taken by Lo et al. (2009; left panels) and significance weights w for the different points in the maps (right panels). White colour in the weight map indicates a significance of unity corresponding to a median signal-to-noise ratio of 25 or above. For the ¹³CO map, only pixels close to the map boundary have a lower S/N, i.e. w< 1.