Abstract

" The University of Tokyo Atacama Observatory (TAO) is a project to construct a 6.5m infrared-optimized telescope at the summit of Co. Chajnantor, 5,640 m altitude, in northern Chile, promoted by Institute of Astronomy, University of Tokyo. Thanks to the high altitude and low water vapor, continuous window from 0.9 to 2.5?m as well as new windows at wavelength longer than 25?m appears. The site shows extremely low precipitable water vapor of 0.5mm (25 percentile), and fraction of usable night is more than 80%. Measured median seeing is 0"".69, which is comparable or better than major observatories over the world. Prior to the 6.5m telescope, a 1m pathfinder telescope called miniTAO is installed and started observations in 2009. Its successes of Paschen ? imaging at 1.875 ?m and mid-infrared observations at 30?m confirm promising capabilities of the site. The 6.5m telescope is now at a design phase, and two facility instruments are now being constructed, which are a near-infrared imager/multi-object spectrograph with a field of view of 9'.6 and a mid-infrared imager/spectrograph for observations in 2 to 38?m. © 2010 SPIE. "