Description
Based on measurements with the Effelsberg 100-m telescope, a multiline study of molecular species is presented toward the southwestern source of the gravitational lens system PKS 1830-211, which is by far the best known target for studying molecular gas in absorption at intermediate redshift. Determining line parameters and optical depths and performing large velocity gradient radiative transfer calculations, the aims of this study are (1) to evaluate physical parameters of the absorbing foreground gas at z~0.89, in particular its homogeneity, and (2) to monitor the spectroscopic time variability caused by fluctuations in the z~2.5 background continuum source.
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