Astronomy in the region 1-0.1mm wavelengths

Measurements in five different passbands in the spectral region below 20/cm were made with a liquid helium-cooled radiometer in two flights at approximately 40 km altitude. The equivalent temperatures are given for passbands of 1 to 5.4, 7.8, 7.9, 11.1, and 18.5/cm. The results are consistent with a 2.7 K thermal radiation background. Atmospheric radiation of uncertain magnitude dominates the region above 11/cm.