Far-IR Observations of Active Regions at Sunspots with a Balloon-Borne 60 cm Telescope

Far-infrared continuum observations of the sun provide a straightforward method of measuring the temperature of various levels of the transition region between photosphere and chromosphere which is characterized by a temperature minimum. These observations allow the determination of the spectral brightness temperature averaged over the disk as well as structure and variability of the solar atmosphere: center-to-limb variation, solar maps, active regions around sunspots, plages, solar oscillations and flares. Observations of the solar emission spectrum at wavelengths between 10 μm and 1000 μm up to 1975/1976 were reviewed by Mankin |1|.