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Proceedings Paper

Evaluations of new atmospheric windows at thirty micron wavelengths for astronomy
Author(s): Takashi Miyata; Shigeyuki Sako; Takafumi Kamizuka; Tomohiko Nakamura; Kentaro Asano; Mizuho Uchiyama; Masahiro Konishi; Mizuki Yoneda; Naruhisa Takato; Yuzuru Yoshii; Mamoru Doi; Kotaro Kohno; Kimiaki Kawara; Masuo Tanaka; Kentaro Motohara; Takeo Minezaki; Toshihiko Tanabe; Tomoki Morokuma; Yoichi Tamura; Tsutomu Aoki; Takao Soyano; Ken'ichi Tarusawa; Hidenori Takahashi; Shintaro Koshida; Natsuko M. Kato
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Paper Abstract

Thirty micron has remained one of unexplored frontiers of ground-based astronomical observations. Recent developments of extreme high sites including the Chajnantor TAO site (5,640m) enable us to access the this wavelengths from the ground. The expected transmittance seems clear enough for astronomical observations, but practical evaluations based on astronomical data has not been carried out yet. We have analyzed images obtained at the 31.7 micron with a mid-infrared camera MAX38 attached on a mini-TAO 1.0-meter telescope. 109 images of a star IRC+10420 and 11,114 images of the sky have been reduced. Clear relationship between the measured photocurrents and the perceptible water vapor has been found. Simple estimation of the photocurrents with of the ATRAN model gives good agreements with the measurements, indicating that the ATRAN model reproduce the atmospheric transmittance reasonably well. This also supports our assumption that the scaling factor 0.85 of the PVW at the Chajnantor TAO site to the PWV at the APEX. The average transmittance in the 31.7 micron is achieved to be over 20% when the PWV below 0.6 mm. In some cases clear degradation up to 10% in the transmittance is found. It may be caused by droplets of liquid or iced water with a size over 10 micron although the causes are not exactly specified. Diurnal time variations of the sky photocurrents are also investigated. The sky is sometimes bright and usually unstable in the twilight time. On the other hand the sky around the noontime does not show clear difference from the night sky. It may suggest that the observing condition at the thirty micron windows remain good even in the daytime.

Paper Details

Date Published: 17 September 2012
PDF: 8 pages
Proc. SPIE 8444, Ground-based and Airborne Telescopes IV, 84446B (17 September 2012); doi: 10.1117/12.925258
Show Author Affiliations
Takashi Miyata, Institute of Astronomy, The Univ. of Tokyo (Japan)
Shigeyuki Sako, Institute of Astronomy, The Univ. of Tokyo (Japan)
Takafumi Kamizuka, Institute of Astronomy, The Univ. of Tokyo (Japan)
Tomohiko Nakamura, Institute of Astronomy, The Univ. of Tokyo (Japan)
The Univ. of Tokyo (Japan)
Kentaro Asano, Institute of Astronomy, The Univ. of Tokyo (Japan)
Mizuho Uchiyama, Institute of Astronomy, The Univ. of Tokyo (Japan)
Masahiro Konishi, Institute of Astronomy, The Univ. of Tokyo (Japan)
Mizuki Yoneda, Planetary Plasma and Atmospheric Research Ctr., Tohoku Univ. (Japan)
Naruhisa Takato, Subaru Telescope, National Astronomical Observatory of Japan (United States)
Yuzuru Yoshii, Institute of Astronomy, The Univ. of Tokyo (Japan)
Mamoru Doi, Institute of Astronomy, The Univ. of Tokyo (Japan)
Kotaro Kohno, Institute of Astronomy, The Univ. of Tokyo (Japan)
Kimiaki Kawara, Institute of Astronomy, The Univ. of Tokyo (Japan)
Masuo Tanaka, Institute of Astronomy, The Univ. of Tokyo (Japan)
Kentaro Motohara, Institute of Astronomy, The Univ. of Tokyo (Japan)
Takeo Minezaki, Institute of Astronomy, The Univ. of Tokyo (Japan)
Toshihiko Tanabe, Institute of Astronomy, The Univ. of Tokyo (Japan)
Tomoki Morokuma, Institute of Astronomy, The Univ. of Tokyo (Japan)
Yoichi Tamura, Institute of Astronomy, The Univ. of Tokyo (Japan)
Tsutomu Aoki, Kiso Observatory, Institute of Astronomy, The Univ. of Tokyo (Japan)
Takao Soyano, Kiso Observatory, Institute of Astronomy, The Univ. of Tokyo (Japan)
Ken'ichi Tarusawa, Kiso Observatory, Institute of Astronomy, The Univ. of Tokyo (Japan)
Hidenori Takahashi, Institute of Astronomy, The Univ. of Tokyo (Japan)
Shintaro Koshida, Institute of Astronomy, The Univ. of Tokyo (Japan)
Natsuko M. Kato, Institute of Astronomy, The Univ. of Tokyo (Japan)


Published in SPIE Proceedings Vol. 8444:
Ground-based and Airborne Telescopes IV
Larry M. Stepp; Roberto Gilmozzi; Helen J. Hall, Editor(s)

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