Far-infrared observations of the galactic Cygnus region and Mars with a 60 cm diameter balloon-borne telescope

We have introduced secondary-mirror chopping in our balloon-borne far-infrared 60 cm Ø telescope equipped with He-cooled filters and a composite silicon bolometer with an NEP of 1.3 10^–14 W/Hz^1/2 for imaging, radiometry and spectroscopy of the Cygnus region at the wavelengths 80 m, 130 m and 310 m. The modified system was flown on September 26/27, 1990 with a 380'000m³ hydrogen balloon at the CNES station at Aire/Adour, France. Observations were performed at a platform height of 39 km during 5 hrs. We made successful measurements on the complexes DR21 and S106 of the Cygnus region as well as on Mars at the wavelengths mentioned.