Beobachtungsbedingungen für Infrarot-Photometrie auf dem Calar Alto

The 1.2-m telescope on Calar Alto has been in service for about two years. During this time investigations were conducted with two photometers, including a 5-20 micron photometer with a bolometer as detector and a 1-5 micron photometer with an InSb detector. Calar Alto has an altitude of 2160 m. It is located in the arid climate of the southeast of Spain. Climatic conditions are, therefore, similar to those found in the case of U.S. IR observatories situated on mountains of comparative altitude in Arizona and California. The quality of the observational conditions is essentially determined by three factors, including the atmospheric conditions, the telescope, and the photometer/detector system. Data concerning the measured extinction values and the dependence of the effective wavelength on atmospheric extinction are presented in tables.