Measurements of atmospheric water vapor above Mauna Kea using an infrared radiometer

This paper presents the first results from a prototype infrared radiometer which has been developed to measure Variations in atmospheric water vapor c olumn abundance from high altitude sites. The performance of the infrared r adiometer is compared and contrasted with that of a water vapor monitor ope rating at radio frequencies. Analysis shows that the infrared radiometer ca n measure variations at the level of similar to 1 mum precipitable water va por (pwv) in an integration time of Is when the total column abundance is s imilar to 0.5 mm pwv. Since variations in atmospheric water vapor are the d ominant source of phase noise in (sub)millimeter astronomical interferometr y, an instrument capable of rapid and high sensitivity water vapor measurem ents has the potential to provide the necessary phase correction informatio n for interferometric arrays.