Left panel: observed 557 GHz spectrum (solid black line) at the B1 position compared to the spectrum computed with the Monte Carlo code (solid red line) where X(H₂O) = 6 × 10^-8. Note that the narrow emission component is not included in the model. Right panel: the observed spectrum (black solid line) at the HH 313 A position compared to the computed spectrum (red solid line). The model has two components, an extended component (dashed line) and a small hot component (dashed-dotted line). Note that blue-shifted emission, originating from GSS 30, is visible in the observed line profile.