Observations of the CO(2-1) at 230.5 GHz and CO(3-2) were made using the 10.4 m telescope of the Hawaiian Caltech Submillimeter Observatory in 1988 and 1989. Measurement of sensitive line profiles from the highly evolved carbon star/proto-planetary nebula CRL 618 showed a very high velocity molecular outflow with V(0) greater than 190 km/sec. CRL 618 appears to be at the stage of beginning to ionize both the fast and slow molecular winds, as shown by the shapes of the millimeter-wavelength recombination lines by Martin-Pintado et al. (1988) and the width of the H-alpha line by Carsenty and Solf (1982).
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Gammie et al. (1989) studied this question.