Development of Mid-IR High resolution spectrograph toward the observation of interstellar and 
planetary atmospheric molecules, with preliminary results and future project

Prof Yasuhiro Hirahara (Department of Earth and Planetary Sciences, Graduate School of Environmental 
Studies, Nagoya University, Nagoya 464-8602, Japan)  [名古屋大學 平原靖大教授] / yasu@nagoya-u.jp


We developed GIGMICS (Germanium Immersion Grating Mid-Infrared Cryogenic Spectrograph), which operates at 
N-band (8-13 μm in wavelength λ) with maximum resolving power  R(≡λ /Δλ) ~ 40,000. A single crystal 
germanium echelle immersion grating (30 × 30 × 72 mm) for collimated beam size of 28 mmφ was fabricated 
by utilizing ultra precision micro-grinding method coupled with the ELID (ELectrolytic In-process 
Dressing) technique. We have conducted the astronomical observation of GIGMICS by the Kanata 1.5-m 
telescope at Higashi-Hiroshima Observatory, Japan. The observation of Venus showed the significant carbon 
isotope anomaly of CO2 in the Venusian mesosphere for the first time.

University of Hawaiʻi, Institute for Astronomy has proposed to establish and operate the PLANETS 
(Polarized Light from Atmospheres of Nearby Extra-Terrestrial Systems) 1.9-m telescope facility located 
within the Haleakalā High Altitude Observatory Site near the summit of Haleakalā with 3000-m altitude. 
Just recently, on Mar. 4, 2017, the proposal has successfully passed the environmental assessment by the 
BLNR (Board of Land and Natural Resources), State of Hawaiʻi. On receiving the result, the construction 
of telescope will begin with the scheduled completion in two years later.  GIGMICS shall be set at the 
Gregorian focus of the PLANETS, and be used for the deep searches for the vibration-rotation spectra of 
molecules existing in the various astronomical object including (exo-)planetary atmosphere.