Abstract
A spectral radiometer to measure atmospheric radiance has been constructed using a helium-cooledphotoconductor detector. The radiometer is of medium resolution (δλ/λ ∼ 2%) and its advantages areits narrow beam ∼10-6 sr) and accuracy in the absolute radiance measurement (1% of a blackbody atambient temperature). Some examples of spectra made with the instrument are presented.