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

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 mum (51-233 cm(-1)) with both medium and high spectral resolving power. Also 'Neptune's 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. (C) 2004 COSPAR. Published by Elsevier Ltd. All rights reserved.