Comparison of the measured and retrieved spectra for two cases. The left panel shows a case where the measured spectral line shape is well reproduced by the retrieved spectral line. The right panel shows a case where the retrieved spectral line shape does not agree well with the observed line. The observed line shows an extended absorption area for positive Doppler velocities, while the retrieved line lacks this feature. The shoulder in the absorption line is due to molecules moving away from the observer (MIRO) and cannot be explained within the approximations of the coma model used in this study.