Maps of C¹⁸O 2–1 integrated emission (line contours) and 1.3 mm continuum emission (colour map). Contours are drawn starting from 3σ in steps of 6σ (see Table 2 for C¹⁸O and continuum 1σ rms sensitivities). Synthesised beams of the C¹⁸O and continuum emission are shown in the lower left corners as respectively black and a shaded ellipses. Note that the beam sizes only differ significantly for the targets where extended data is available for the C¹⁸O emission. The blue symbols mark the source positions from the VANDAM survey (Tobin et al. 2016), with crosses indicating single protostars and triangles indicating multiple systems with projected separations <0.8′′.