Integrated intensities of the CO J = 8 → 7 (left) and CO J = 9 → 8 (right) lines towards the C1 clump are shown in the colour scale. The contours are mass surface density from Butler & Tan (2012), with the contours starting at 0.075 g cm^-2 and increasing by increments of 0.075 g cm^-2. The blue diamonds are the locations of the C1-N and C1-S cores, with the top left core being C1-N. The blue circles have diameters equal to the half power beam width of the Herschel beams.