SIMBAD references

Astronomical observations of (sub)millimeter wavelength pure rotational emission lines of the second most abundant molecule in the Universe, CO, hold the promise of probing regions of high temperature and density in the innermost parts of circumstellar envelopes. The rotational spectrum of vibrationally excited CO up to v=3 has been measured in the laboratory between 220 and 1940GHz with relative accuracies up to 5.2x10^–9, corresponding to ∼5kHz near 1THz. The rotational constant B and the quartic distortion parameter D have been determined with high accuracy and even the sextic distortion term H was determined quite well for =1 while reasonable estimates of H were obtained for v=2 and 3. The present data set allows for the prediction of accurate rest frequencies of vibrationally excited CO well beyond 2THz.