Comparison of the H₂O (black) and HO (red) 1₁₀ −1₀₁ spectra for IRAS4B where the H₂O spectrum has been scaled down such that the peak intensities are the same. The green line indicates the baseline. The blue lines indicate the approximate velocities of the CH transitions from the other sideband in the HO observations. The third component of the CH triplet is just beyond the plotted range but is also detected.