Average Titan spectrum from NIRSpec (black) compared with a radiative transfer calculation in which the surface albedo decreases smoothly with wavelength beyond 4.9 μm (red). The blue line shows the difference between the observed and synthetic spectra, shifted by 0.005 for clarity. The 5.11-μm absorption feature is not reproduced by the model. The small mismatch below 4.93 μm is attributed to a non-LTE CO emission component not included in the model.