Session 30 - Radio Astronomy, Yesterday, Today and Tomorrow - I.
Oral session, Tuesday, June 11
Union Theater,

[30.05] The Caltech Submillimeter Observatory (CSO)

T. G. Phillips (Caltech)

The CSO consists of a 10.4 m Leighton telescope on the 14,000^\prime summit of Mauna Kea, Hawaii. The Earth's atmosphere permits observations up to 900 GHz (\sim 320 \mum) and the telescope has been measured and set by a shearing interferometer technique, to an accuracy in the 15--20 \mum range. The observatory has SIS heterodyne receivers operating from about 200--850 GHz with noise temperatures only a few times the quantum limit, except for the highest band. It also has bolometers for the same range and a new 20 pixel bolometer camera for the 450 and 350 \mum windows, which is nearly background limited.

The submillimeter band contains fundamental information for star-formation process, interstellar medium physics and chemistry, nearby galaxy structure and possibly for distant forming galaxies. It also can be used for fields as diverse as planetary atmospheres and cosmology, through the Sunyaev-Zel'dovich (S-Z) effect.

Recent results from the CSO include 350 \mum maps of high-mass star-forming regions, showing outlying regions of low-mass star-formation, also maps of the Galactic center Giant Molecular Clouds, all at about 10^\prime\prime resolution. There have been molecular line surveys of Giant Molecular Clouds revealing a line forest'' extending through the 1.3 mm to the 450 \mum bands. The physics of the Interstellar Medium has been studied in terms of the manifestations of turbulence and also the spatial character of the ubiquitous carbon atom and its relation to the penetration of the UV field into molecular clouds.

CO lines have been studied in galaxies up to z\sim0.1 and up to the J=6--5 transition. Galaxies have also been studied in dust emission and a deep survey is underway with the bolometer camera to search for primeval galaxies.

Other exciting topics include the detection of S-Z clusters, FTS studies of planetary atmospheres and the Earth's atmosphere, and interferometry studies with the JCMT of 50 AU disks around HL Tau and L 1551.