Rotational diagrams of CO for all objects in our sample. The base-10 logarithm of the number of emitting molecules from a level u, , divided by the degeneracy of the level, g_u, is shown as a function of energy of the upper level in kelvins, E_up. Detections are shown as filled circles, whereas three-sigma upper limits are shown as empty circles. Blue lines show linear fits to the data and the corresponding rotational temperatures. The vertical red line in the G34.26+0.15 panel shows the dividing line between the warm and hot components as seen in rotational diagrams of low-mass YSOs. Errors associated with the fit are shown in brackets.