Atmospheric Noise in the Far Infrared (300-3000 μm)

Noise measurements in the frequency regions 5-200 HZ and 5.2 x 10^-4 -8.3 x 10^-3 Hz have been performed in the wavelength region between 300 and 3000 mu m from the high altitude observatory of Tests Grigia, Italy (3.500 m). In the high frequency region a specially designed Ge bolometer operating in background-limited-infrared-photoconductor conditions matched to a 1.5-m telescope has been used, while at low frequency a radiometer designed for atmospheric transmittance measurements was employed. In both regions no excess noise with respect to the photon noise relative to 300-K blackbody has been detected.