SIMBAD references

We report the first detection of methyl radicals (CH₃) in the upper atmosphere of Saturn. Emission from the ν₂ Q-branch of CH₃ at 16.50 µm was detected from observations with the Short-Wavelength Spectrometer of the ISO satellite. A CH₃ column density in the range 1.5-7.5x10¹³molec/cm² is derived, taking into account uncertainties in the data calibration, CH₃ band strength, and atmospheric model.
Result. are compared with predictions of photochemical models. The CH₃ abundance is mostly sensitive to the poorly known methyl recombination rates and to the eddy mixing profile. The ISO observations imply either CH₃ recombination rates larger than used in current photochemical models, or an eddy mixing coefficient near the methane homopause smaller than inferred from Voyager ultraviolet measurements.