Atmospheric Noise in the far Infrared

Noise measuraments in the frequency region 6.5×10
⁻⁵
- 1.6×10
⁻²
Hz and 5-200 Hz have been performed between 300 and 3000 microns at the observatory of Testa Grigia (3500 m.a.s.l.). During clear and dry days and ninths no excess of noise has been detected with respect to the photon noise of a 300°K blackbody.