Far Infrared Absorption of the Atmosphere Above 4.2 km

Observations of the atmospheric absorption spectrum have been made from the site of the Mauna Kea Observatory (elevation 4.2 km). Using an interferometer and cryogenic barometer, we have obtained solar spectra with a resolution of better than 0.2 cm−1 in the frequency range below 30cm−1 (λ≳300μ). Interesting features of these spectra include five molecular oxygen rotational transitions and the presence of structure attributable to a number of other atmospheric constituents. In addition a comparison of the experimental results to theoretical water vapor spectra has provided an estimate of the achievable atmospheric transmission from this site for astronomical observations in this spectral range.