Far-infrared telescope

It should not be thought that OH always exhibits the unusual behaviour described above the recent developments in tunable far-infrared sources have had an important impact in astronomy, so that interstellar rotational transitions can now be observed. We described an airborne far-infrared telescope in the first part of this chapter, and figure 10.60 shows two examples of interstellar OH rotational transitions, observed by Watson, Genzel, Townes and Storey [170],... 

It should be noted that the rotational spectroscopy of CO confined to a single vibrational level, usually the ground v = 0 level, provides only a limited amount of information about molecular structure. In the field of vibration-rotation spectroscopy, however, CO has been studied extensively and particular attention paid to the variation of the rotational and centrifugal distortion constants with vibrational quantum number. Vibrational transitions involving d up to 37 have been studied with high accuracy [78, 79, 80], and the measurements extended to other isotopic species [81] to test the conventional isotopic relationships. CO is, however, an extremely important and widespread molecule in the interstellar medium. CO distribution maps are now commonplace and with the advent of far-infrared telescopes, it is also an important... 

---