The University of Tokyo Atacama Observatory Project is to construct and operate a 6.5m infrared telescope at the summit of Co. Chajnantor (5640m altitude) in northern Chile, promoted by the Institute of Astronomy of the University of Tokyo. Thanks to the dry climate (PWV~0.5mm) and the high altitude, excellent observation condition in the NIR to MIR wavelengths is achieved. The telescope has two Nasmyth foci where two facility instruments, SWIMS for the near-infrared and MIMIZUKU for the mid-infrared, are installed and two folded- Cassegrain foci for carry-in instruments. All these four foci can be switched by rotating a tertiary mirror. The final focal ratio is 12.2 and the foci have large field-of-view of 25 arcmin in diameter. <p> </p>We adopted a 6.5-m F/1.25 light-weighted borosilicate honeycomb primary mirror and its support system that are developed by Steward Observatory Richard F. Caris Mirror Lab. An enclosure has the shape of carousel, and large ventilation windows with shutters control the wind to flush heat inside the enclosure. A support building with a control room, a mirror coating system and maintenance facilities is located at the side of the enclosure. The mirror coating system consists of a large aluminizing chamber and a mirror washing facility. The operation of the telescope will be remotely carried out from a base facility at San Pedro de Atacama, 50km away from the summit. Development of the two facility instruments has already been completed and they are transported to Hilo, Hawaii in 2017. We are going to carry out engineering observations of those instruments on the Subaru telescope for clearing up technical issues and verifying their performance. The existing summit access road from the ALMA concession area was laid in 2006, however, it is too narrow to carry large components of the telescope and the ancillary facilities such as the primary mirror, its cell, and the aluminizing chamber. The road is being expanded so that it has the width of <5m for straight portion and <7m for curved portion.. The telescope mount and the enclosure are being pre-assembled for functional and performance tests in Japan. All telescope system will be assembled at the summit and see the engineering first light early 2019.
The University of Tokyo Atacama Observatory (TAO) is a project to construct a 6.5-meter telescope optimized for infrared observations at the summit of Co. Chajnantor, 5,640 m altitude. The high altitude and low water vapor (0.5mm in 25% percentile) of the site provide wide wavelength coverage from 0.3 to 38 micron including continuous window from 0.9 to 2.5 micron and new windows at wavelength longer than 25 micron. We report on the design and the current status of the mirror, the telescope, the summit and the base facilities in this paper.
A basic design of enclosure and support facilities for the University of Tokyo Atacama observatory (TAO) 6.5-m telescope is described in this paper. The enclosure facility has a carousel shape with an open-space near the ground surface. The upper carousel rotates independently of the telescope. Horizontally opened slit doors, a dozen ventilation windows, wind and moon shields, and an overhead bridge-crane are equipped. For safety reasons, most of maintenance walkways are placed inside of the enclosure facility. An observation floor of the enclosure facility is connected to the support facility via a bridge for maintenance of observation instruments and a primary mirror of the telescope. Air inside of the enclosure and support facilities is exhausted to an underground tunnel.