Intensity-weighted mean velocity (first moment) maps of H₂CO (3_0,3 − 2_0,2) showing the large-scale kinematics of the full CORE sample. The contours correspond to the continuum maps imaged with uniform weighting as presented in Beuther et al. (2018). The outermost three contours correspond to 5, 10, and 20σ levels, then increasing in steps of 15σ. For IRAS 23151, NGC753 8IRS1, NGC753 8IRS9 and AFGL2591 the outermost three contours correspond to 5, 15, and 40σ levels, then increasing in steps of 25σ (see Table 3 for σ values). The synthesised beam is shown in the bottom left corner and a scale bar in the bottom right corner of each panel. When displayed in Adobe Acrobat, it is possible to switch to the first moment map of CH₃OH(4 − 3) and back to the first moment map of H₂CO(3_0,3 − 2_0,2) for comparison.