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We used the Effelsberg 100 m and IRAM 30 m telescopes to observe vibrationally excited cyanoacetylene (HC 3 N) in several rotational transitions toward the proto-planetary nebula CRL 618. Lines from 9 different vibrationally excited states with energies ranging up to 1600 K above ground were detected. The lines show P Cygni profiles indicating that the HC 3 N emission originates from an expanding and accelerating molecular envelope. The HC 3 N rotational temperature varies with velocity, peaks at 520 K, 3 km s −1 blue-shifted from the systemic velocity and decreases with higher blueshift of the gas. The column density of the absorbing HC 3 N is 3-6×10 17 cm −2 . We modeled spectra based on spherical models of the expanding envelope which provide an excellent fit to the observations, and discuss the implications of the models. Additionally, lines from 13 C substituted cyanoacetylene were observed. They can be used to constrain the 12 C/ 13 C ratio in this source to 10 ± 2.

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We have observed the 1 10 -1 01 pure rotational transitions of both H 2 16 O and H 2 18 O toward Sagittarius B2 using the Submillimeter Wave Astronomy Satellite. The spectra thereby obtained show a complex pattern of absorption and-in the case of H 2 16 O-emission, with numerous features covering a wide range of LSR velocities (Ϫ130 to 130 km s Ϫ1 ) and representing absorption both in gas associated with Sgr B2 as well as by several components of foreground gas along the line of sight. The ortho-water abundance derived for the absorbing foreground gas is ∼ relative to H 2 . Ϫ76 # 10

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