The University of Tokyo Atacama Observatory 6.5 m telescope: Development of the telescope and the control system

Takeo Minezaki; Tomoki Morokuma; Yuzuru Yoshii; Mamoru Doi; Takashi Miyata; Kotaro Kohno; Masuo Tanaka; Kentaro Motohara; Shigeyuki Sako; Toshihiko Tanabe; Bunyo Hatsukade; Masahiro Konishi; Hidenori Takahashi; Takafumi Kamizuka; Hiroaki Sameshima; Kentaro Asano; Natsuko Kato; Mizuki Numata; Tsutomu Aoki; Takao Soyano; Ken'ichi Tarusawa; Mitsufumi Nishimura; Takayuki Seki; Naruyo Kajitani; Yuji Ikeda; Tomoshiro Yoshikawa; Yoshitaka Matsumoto; Shintaro Nakamaru

doi:10.1117/12.2562223

13 December 2020 The University of Tokyo Atacama Observatory 6.5 m telescope: Development of the telescope and the control system

Takeo Minezaki, Tomoki Morokuma, Yuzuru Yoshii, Mamoru Doi, Takashi Miyata, Kotaro Kohno, Masuo Tanaka, Kentaro Motohara, Shigeyuki Sako, Toshihiko Tanabe, Bunyo Hatsukade, Masahiro Konishi, Hidenori Takahashi, Takafumi Kamizuka, Hiroaki Sameshima, Kentaro Asano, Natsuko Kato, Mizuki Numata, Tsutomu Aoki, Takao Soyano, Ken'ichi Tarusawa, Mitsufumi Nishimura, Takayuki Seki, Naruyo Kajitani, Yuji Ikeda, Tomoshiro Yoshikawa, Yoshitaka Matsumoto, Shintaro Nakamaru

Author Affiliations +

Proceedings Volume 11445, Ground-based and Airborne Telescopes VIII; 114452R (2020) https://doi.org/10.1117/12.2562223
Event: SPIE Astronomical Telescopes + Instrumentation, 2020, Online Only

Conference Poster

Abstract

The University of Tokyo Atacama Observatory Project is to construct a 6.5 m infrared-optimized telescope at the summit of Co. Chajnantor (5640 m altitude) in northern Chile. The telescope optics uses a Ritchey-Chretien type layout, with an under-sized secondary mirror to reduce stray light caused by thermal emission from the telescope structure. The primary mirror is a F/1.25 lightweight borosilicate glass (Ohara E6) mirror with honeycomb structure, which is developed by Steward Observatory Richard F. Caris Mirror Lab. The telescope has two Nasmyth foci and two folded-Cassegrain foci, which can be switched by rotating a tertiary mirror. The final focal ratio is 12.2 with a field of view of 25 arcmin in diameter. The telescope mount is a tripod-disk alt-azimuth mount. Both the azimuth and elevation axes are supported by and run on hydrostatic bearings, and they are driven by friction drives with servo motors, which are controlled by the telescope control system. It also controls the hexapod mount of the secondary mirror and the pneumatic actuators of the primary mirror support to keep good image quality during the observation. An off-axis Shack-Hartmann sensor installed in each focus measures the wavefront aberration of the telescope optics, then the misalignment between the secondary and primary mirrors is corrected by adjusting the hexapod mount while other aberrations are corrected by the deformation of the primary mirror. The force distribution of the actuators for correction will be calculated by fitting the wave-front errors with a series of bending modes of the primary mirror.

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Takeo Minezaki, Tomoki Morokuma, Yuzuru Yoshii, Mamoru Doi, Takashi Miyata, Kotaro Kohno, Masuo Tanaka, Kentaro Motohara, Shigeyuki Sako, Toshihiko Tanabe, Bunyo Hatsukade, Masahiro Konishi, Hidenori Takahashi, Takafumi Kamizuka, Hiroaki Sameshima, Kentaro Asano, Natsuko Kato, Mizuki Numata, Tsutomu Aoki, Takao Soyano, Ken'ichi Tarusawa, Mitsufumi Nishimura, Takayuki Seki, Naruyo Kajitani, Yuji Ikeda, Tomoshiro Yoshikawa, Yoshitaka Matsumoto, and Shintaro Nakamaru "The University of Tokyo Atacama Observatory 6.5 m telescope: Development of the telescope and the control system", Proc. SPIE 11445, Ground-based and Airborne Telescopes VIII, 114452R (13 December 2020); https://doi.org/10.1117/12.2562223

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