Ohana project
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[edit] General view of the project
As you may read in other articles, ‘ohana means "family" in Hawaiʻian. But in this case, OHANA means Optical Hawaiian Array for Nanoradian Astronomy.
This project aims to use seven big telescopes atop the Mauna Kea, Hawaiʻi Big Island, in an interferometer configuration. The Mauna Kea is a former volcano which height is 13,600 ft (4,145 m). The Mauna Kea is a very good place for telescopes which probe the universe in the optical and infrared wavelengths: it is very high and there is not a lot of light pollution.
[edit] The telescopes involved in the project
Among the several telescopes belonging to the Mauna Kea Observatory only seven are involved in the 'OHANA project :
- Two Keck telescopes. They both have a 10 m diameter primary mirror.
- Subaru. It has a 8.2 m primary mirror.
- Gemini North. It has a 8 m primary mirror.
- CFHT. The Canada France Hawaii Telescope has a Prime Focus/Cassegrain configuration with a usable aperture diameter of 3.58 meters.
- IRTF. The Infrared Telescope Facility is a 3 m telescope.
- UKIRT. The United Kingdom Infrared Telescope is a 3.8 m telescope.
[edit] Several steps of the project
What is important to know about the project is that the big improvement is the use of optic fiber instead of mirrors to guide the beams in the interferometer recombination system.
So before doing some tests with the telescopes, the scientists had to prove that the elements used with the optics fiber were trustworthy (for example, the off-axis parabolla, used to inject the beams in the optics fiber). Those tests were partly carried out on the IOTA Observatory.
The next step, was to use two optics fiber of 300 m between Keck I and Keck II to look at the same source. This step was achieved on June 15th, 2005. This step was a big relief for the project leader. It meant that the project was about to move on.
The current step of the project is the use of the CFHT and Gemini North together. To do that, a long delay line was integrated in the Meudon Observatory to be then used in the CFHT Coudé room. Currently, the delay line is to be shipped to Hawai'i to be integrated in the Coudé room.
The next step is the use of the two Keck and Subaru, then the use of Gemini North, the CFHT and UKIRT together, and finally, the use of all telescopes together.
