Far-infrared spectroscopy of the giant planets: measurements of ammonia and phosphine at Jupiter and Saturn and the continuum of Neptune Original Research Article

We detected rotational transition features of ammonia and phosphine in the far-infrared spectra of Jupiter and Saturn and measured the far-infrared continuum of Neptune with high photometric accuracy. These observations were made with the long-wavelength spectrometer (LWS) aboard the infrared space observatory (ISO). The LWS covered the wavelength region between 43 and 197 μm (51–233 cm−1) with both medium and high spectral resolving power. Also Neptuneʹs continuum was measured with the LWS and at shorter wavelengths with the ISO short-wavelength spectrometer (SWS). The spectra observed in the far-infrared are compared to synthetic spectra calculated from atmospheric radiative transfer models using expected values for the constituent vertical concentration profiles.