INTERSTELLAR AND LABORATORY SPECTROSCOPY IN THE TERAHERTZ REGION

Abstract

From Cologne, we operate the KOSMA 3-m radiotelescope (Kolner Observatorium fur Submillimeter Astronomie) located on the Gornergrat at an altitude of 3200 m near Zermatt, Switzerland. The telescope is used mainly for large scale molecular (CO, CN) line surveys and, in future, for atomic carbon (CI) line maps in selected galactic sources, such as Orion A and B, the Rosette nebula, S140, and IC 1396. During the winter months for about 20% of the time, the measured precipitable water vapor content is lower than 1mm, which enables us to observe up to the 860 GHz window. For this purpose, the reflector of the telescope will be exchanged (1995/1996) with a new one having a surface accuracy of $10 \mu$m rms. The work with the telescope is supported by high resolution laboratory spectroscopy, which has recently been expanded into the terahertz region. We have studied the spectra of many astrophysically interesting molecules and radicals up to 1.2 THz, some of which will be discussed; e.g., SO, CN, SH. Technical development in the Cologne microstructure laboratory has produced SIS-mixer junctions on Nb-basis which operate up to 800 GHz. A short discussion of new technical aspects will be presented.