The Kölner Observatorium für SubMillimeter Astronomie (KOSMA) was a 3-m radio telescope for submillimeter astronomy located at 3,135 m on Gornergrat near Zermatt (Switzerland). It was operated by the "I. Physikalisches Institut" (Cologne, Germany) and the "Radioastronomisches Institut der Universität Bonn" (RAIUB), University of Bonn. It was equipped with heterodyne receivers covering frequencies between 210 and 880 GHz, corresponding to wavelengths between 0.35 and 1.4 mm, for observations of lines from the interstellar medium.
Because of the good climatic conditions at the altitude of 3135 m (10285 ft), astronomical observatories have been located in both towers of the Kulmhotel at Gornergrat since 1967. In 1985, the KOSMA telescope was installed in the southern tower by the Universität zu Köln and, in the course of 1995, replaced by a new dish and mount. In the northern tower, a 1.5 m infrared telescope was operated until 2005 by an Italian association of universities (TIRGO).