Topics 2015.03.23

Progress of the Hawaiian planetary telescopes "T60 & PLANETS"


Progress of the Hawaiian planetary telescopes "T60 & PLANETS"

Since 1999, the Planetary Plasma and Atmospheric Research Center and the Planetary and Space Physics Group of Tohoku University have been conducting observation and educational activities using the nation's only 60cm telescope dede nuclear power plant accident caused by the disaster of March 11, 2011, long-term telescopic observation in the area was made difficult due to the radiation levels in the area reaching up to 6.5 microsieverts per hour. After reviewing several alternate sites, it was determined that the summit of Haleakalト閼€ in Hawaii offered optimum conditions for observations. Upon approaching the University of Hawaii, the construction was readily agreed as a contribution to the reconstruction efforts after the disaster.

Since then, a project was started to relocate the telescope located in Iitate to Haleakalト閼€ in Hawaii. As the summit is located within Haleakalト閼€ National Park, there were unexpected twists and turns regarding work permits. However, with cooperation from Tohoku University staff, University of Hawaii, and local suppliers, these various difficulties were overcome and the relocation project was continued. Finally, we completed construction of dome building and the relocation of telescope in the beginning of this September. The new facility is the Tohoku University 60-cm Telescope Facility called "T60". The opening ceremony of T60 was carried out at the Haleakala summit on September 8th; in addition, Tohoku University and IfA agreed to sign the scientific cooperate agreement for T60 with the Advanced Technology Research Center of IfA, University of Hawaii.

We installed a mid-infrared heterodyne spectrometer called MILAHI, which has super-high spectral resolution of λ/dλ ~ 10^6-7 and started its initial run attached to T60. The instrumental capability and feasibility were demonstrated by solar observations (terrestrial and solar atmospheres). We are going to Martian observations in Nov 2014 and March-September 2015 for the monitor of lower atmosphere just below MAVEN observations. In addition, a new monochromatic imager with an Occulting mask and a Lyot stop was been developed for T60. We confirmed that the imager successfully decreases diffraction from bright main body by factor of 2-3 for axisymmetric background contamination as well as by order of 1 for cross-shaped background contamination. Long-term monitoring of faint emissions close to the planets, e.g. Jupiter plasma torus, Enceladus torus, will be achieved using this high-dynamic imaging capability with high-spectral resolution.

Furthermore, we are conducting the international telescope project called 'PLANETS' which is characterized by a low-scattering optical system with an 1.8-diameter off-axis main mirror to observe faint emission near a bright object, such as resonant/Rayleigh/Mie scattering surrounding a planet/satellite. PLANETS adopts several new technologies and instrumentation techniques. Off-axis telescopes can have far superior contrast because there are no obstructions in the beam such as secondary mirror supports. This limits the diffraction as well as scattered light from obstructions. This telescope is ideal for coronography and other techniques requiring a stable optical path. By combining expertise from various fields - coronography and high contrast imaging from solar physics, polishing, polarimetry, and adaptive optics, this telescope will make significant advances in several fields. The telescope is proposed for Haleakala, a 3000-meters (10,000-ft) volcano on the island of Maui, Hawai'i, with excellent weather and seeing. The unique capabilities of this telescope will allow advances in the study of circumstellar environments, solar system planetary atmospheres, extrasolar planetary atmospheres and the development of the innovative instrumentation to enable this science. The PLANETS project is carried out as an international collaboration organized by University of Hawai'i Institute for Astronomy (IfA), Tohoku University, and the Kiepenheuer Institute for Solar Physics (KIS) and the National Autonomous Univesity of Mexico (UNAM).

(Assoc. Prof. Takeshi Sakanoi, Planetary Plasma and Atmospheric Research Center)

Link : Planetary Plasma and Atmospheric Research Center

Link : Intensification of international collaborations for planetary plasma and atmospheric dynamics research based on the Hawaiian planetary telescopes


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