We list in Table 1 the observed stars together with some of their characteristics. Distances, expansion velocities, mass loss rates, and spectral types are taken from the compilations of Bujarrabal et al. (1994) and Loup et al. (1993A&AS...99..291). The sample includes C-rich and O-rich objects, some S-stars, a few proto-PN, and a young PN (NGC7027). See paper for more details. In Table 2, we give some of the observational parameters. A_low_ and A_high_ refer to the integrated intensity of the low-frequency and high-frequency fine-structure groups. The intrinsic intensity ratios, R=A_high_/A_low_, are R(1-0)=2 and R(2-1)=1.8. In principle, the observation of several components with different intrinsic strengths allows an estimate of the line optical depth, and the value of R gives an estimate of the envelope thickness.

Cone search capability for table J/A+A/319/235/table1 (Circumstellar envelopes observed in the CN lines)