High resolution photographs of the Sun near 200 nm

A balloon-borne telescope has been flown two times at altitudes higher than 30 km. High resolution pictures of the Sun were obtained at 200 nm, 210 nm, 310 nm, and 460 nm. The spatial resolution for high contrast objects was 0.5 arc sec. At 460 and 310 nm, granulation and faculae are visible. At lambda 200 nm only bright grains of a mean area of 4 arc sec2 and a mean contrast of 47% are found. Though these grains are visible to the center of the disk, they are identified as facular grains. A statistical study of these grains permits the derivation of a facular grain model with a temperature excess of 180 K with respect to the surrounding photosphere starting at the altitude of 180 km. This model successfully predicts the grain observed contrast at the different wavelengths and the intensity excess. (Auth.)