Atmospheric Blur SHOULD NOT Be Considered in Weighing In on the TMT Project

I’m not gonna lie and pretend I know anything about what I’m blogging about here on this TMT project, just putting out some things that I see every now and then.

…Berkley University has found an “improved technique to remove atmospheric blur has produced the sharpest whole-planet picture ever taken from the ground

…The multiple-star technique produces sharp images over a wider area of sky – an area about three times larger than that produced by single-star adaptive optics systems employed on large telescopes such as Keck II and Gemini North in Hawaii

I asked Andrew Cooper about Lighting on the Big Island and he responded with a very interesting read that deals with this Atmospheric Blur.

If these Berkley findings are true, then Atmospheric Blur should not be considered when placing the TMT on top of Mauna Kea as we have now seen that it can be dealt with other ways.

4 Responses

  1. Yes, AO=Adaptive Optics. I just re-read your posting and realized that you wrote the article talking about AO without actually using the words.

  2. Andrew – Just realized what you were talking about when you said AO in your comment above.

    Weren’t you talking about Adaptive Optics?

    Developed by the military in the 1970s, ADAPTIVE OPTICS was used for the first time in 2003 on one of the twin Keck telescopes that straddle the summit of Hawaii’s dormant Mauna Kea volcano.”

  3. The problem with locating something by equator
    is this. There isn’t any mountains as high as Mauna
    Kea in that general location.

    Damon – I would think that with the way the earth’s axis tilts at times, there are places along the equator that are actually closer to space then Mauna Kea. *I don’t know this to be fact though*

  4. No.

    Atmospheric distortion, known to astronomers simply as “seeing” is of the upmost consideration when siting a new telescope.

    Any foreseeable AO system is only able to correct so far, something we call a strehl ratio. Keck’s system, arguably one of the best in the world achieves a strehl of about 60%, meaning we can see an image that is 60% as good as the “perfect” image that could be seen if there were no atmosphere distorting the image. Thus it is critically important that the site be as good as possible, so that the starting point is good, upon which we further improve the image with the AO system. This is worse with the laser, where we get only a 40% improvement.

    Current and planned systems work only in the near infrared. While the infrared is very valuable to astronomy, much can be learned in the visible as well. For the visible wavelengths, red, green, blue, etc., no practical AO systems are available. There continues to be research in this area, but the technical challenges are daunting.

    Good seeing is only one of the advantages of a high altitude site, which also include the low humidity and getting above the dust, haze and aerosols that are present in the lower atmosphere.

    Damon – hmm… I don’t know much about space, light, and the atmosphere, but I sure am learning a thing or two. I still have to think somewhere near the equator would be much better ;)

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