  Cornell University, the California Institute for Technology, and the Jet
Propulsion Laboratory are jointly studying the construction of a 25 m diameter
telescope for submillimeter astronomy on a high mountain in northern Chile.
This Cornell Caltech Atacama Telescope (CCAT) will combine high sensitivity, a
wide field of view, and a broad wavelength range to provide an unprecedented
capability for deep, large area, multi-color submillimeter surveys to
complement narrow field, high resolution studies with ALMA. CCAT observations
will address fundamental themes in contemporary astronomy, notably the
formation and evolution of galaxies, the nature of the dark matter and dark
energy that comprise most of the content of the universe, the formation of
stars and planets, the conditions in circumstellar disks, and the conditions
during the early history of the Solar system. The candidate CCAT site, at 5600
m in northern Chile, enjoys superb observing conditions. To accommodate large
format bolometer cameras, CCAT is designed with a 20 arcmin field of view. CCAT
will incorporate closed loop active control of its segmented primary mirror to
maintain a half wavefront error of 10 mum rms or less. Instrumentation under
consideration includes both short (650 mum-200 mum) and long (2 mm-750 mum)
wavelength bolometer cameras, direct detection spectrometers, and heterodyne
receiver arrays. The University of Colorado, a Canadian university consortium,
and the UK Astronomy Technology Centre on behalf of the UK community are
pursuing participation in the CCAT consortium. When complete early in the next
decade, CCAT will be the largest and most sensitive facility of its class as
well as the highest altitude astronomical facility on Earth.
