Far-infrared-solar imaging from a balloon-borne platform

Far-infrared solar imaging with a balloonborne 60 cm-diameter Cassegrain telescope is described and related to previous solar observations in the millimeter range, the ir, vis and uv spectral regions. Solar images have been taken at 50 m, 80 m and 200 m and represented as brightness temperature maps. The spectral windows observed correspond to the transition zone chromosphere-phocosphere of the solar atmosphere with a characteristic temperature minimum. Temperature enhancements of a few 100 K over the temperature of the quiet sun are reported for active solar regions, e.g. plages and sunspot regions. Far-infrared images provide less spatial resolution but more reliable temperature assignements than corresponding white-light, Ca II K and H pictures.