The spectra of the H₂CO(3_0,3 −2_0,2) and H₂CO(4_0,4 −3_0,3) transitions for the 20 km s^-1 cloud (left) and the 50 km s^-1 cloud (right) plotted on top of each other. The spectra of H₂CO(4_0,4 −3_0,3) were multiplied by a factor of 3.8 and 2.9 in the left and right panels, respectively, to bring the two lines to the same scale. The plots show that the two transitions have comparable width in both sources.