A discussion on infared astronomy - Submillimetre solar radiation at sea level

Abstract
The detection of solar radiation in the 860 μm window at a sea-level site (London, England) is reported. The measurements give a value of 7.2 +/- 2.0db/km of standard atmosphere for the minimum attenuation at the centre of the window. The possibility of submillimetre astronomy from low altitude sites is discussed. We conclude that most of the world’s observatories in temperate or cool climates could make worthwhile measurements in the 730 and 860 μm windows for a limited period each year. Measurements at 350 and 450 μm should be possible from a more limited number of sites in cold climates. Low temperature seems to be the most important criterion in choosing a site with low precipitable water-vapour content.