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World's Largest Telescope Up and Running

Posted by ScuttleMonkey on from the ncc-2893 dept.

apdyck writes "ITWire is reporting that the world's largest telescope is now up and running, conducting one-year series of tests. The Great Canary Telescope, located in the Canary Islands, is the largest telescope in the world at 10.4 m (34') in diameter. Not for your average stargazer! 'The reflective telescope, sometimes also called GranTeCan, uses technology called adaptive optics, in which the mirror changes its shape in order to correct distortions of light caused by the Earth's atmosphere. The telescope is part of the Observatorio del Roque de los Muchachos, located on the island of La Palma, Spain, within the Atlantic Ocean.'"

10 of 120 comments (clear)

  1. No, it's not the world's largest telescope. by CanSpice · · Score: 4, Informative

    It's not the world's largest telescope. There are plenty of telescopes that are larger than this. The James Clerk Maxwell Telescope is about 5 meters in diameter larger. Arecibo is about 295 meters larger.

    And then you've got the array telescopes like VLA and VLBA, if you wanted to get pedantic about effective telescope size.

    1. Re:No, it's not the world's largest telescope. by Ambitwistor · · Score: 4, Informative

      TFA (as opposed to the Slashdot summary) says it's the largest visible/infrared telescope. None of the telescopes you've listed are in that category.

    2. Re:No, it's not the world's largest telescope. by mythosaz · · Score: 3, Informative

      Doesn't matter.

      It's still not the largest optical telescope. SALT is 11.1m and is, like GTC, made of an array of mirrors. The LBT is 2x8.4m mirrors for an effective 11.8 aperture. Also "bigger" than GTC.

      Sure, the LBT isn't fully functional, but neither is GTC.

      SALT is fully operational. SALT is bigger. Article is WRONG.

      http://en.wikipedia.org/wiki/List_of_largest_optic al_reflecting_telescopes

    3. Re:No, it's not the world's largest telescope. by matmota · · Score: 3, Informative
      Well, TFA does mention SALT (South African Large Telescope):

      It is interesting to note that the Hobby-Eberly Telescope, also in the United States--near Fort Davis, Texas in the southwestern part of the state--and the South African Large Telescope have larger mirrors but only a portion of each mirror is able to be used when making observations.
      You might disagree with their interpretation, but they did take the other telescopes into account.
  2. Re:iTWire Strikes Again by OriginalArlen · · Score: 3, Informative
    Whilst faking a huge mirror using interferometry (see also Gemini North and South) gives you resolution, but it won't give you the photons. You've got a huge light bucket, but you're squinting through a couple of eyeholes drilled in the bottom.

    Now, if you want to talk about genuinely huge telescopes -- the GCT is only slightly bigger than the Kecks, after all -- the planned OWL (Overwhelmingly Large Telescope) is probably what you're looking for.

    --

    Everything I needed to know about life, I learnt from Blake's Seven
  3. Advice from a (sort of) newbie astronomer by amstrad · · Score: 5, Informative
    My opinion: Keep the cheaper telescope and have more money to spend on accessories such as

    1. Zero power viewfinder, since the Meade 6x30 is worthless. I use a Telerad. They are great and cheap.
    2. A good 8x50 viewfinder. I use an Antares 8X50 Right Angle Erect Image finder.
    3. A good set of quality eyepieces (you can never have enough)
    4. Some filters (light polution, moon, solar, planetary)
    5. decent, but not expensive, pair of field binoculars
    6. etc. I could go on for ever...

    You might be disappointed if you wait a year, buy the more expensive telescope and have no money left over to buy upgrades.

    Some other points:

    • The best telescope you can buy is the one that you will actually use. My first telescope was an 8" equatorially mounted newtonian. I regret buying such a big and bulky scope. It was so akward to actually get to a field. A pair of tripod mount binoculars might have been better for me as a beginner.
    • I suggest not getting all the fancy computer driven stuff. A good star chart and viewfinder can be much more satisfying. If I can convince you of that then you could get more aperture for the same price with a Dobsonian style telescope.
    • Don't fixate on magnifying power. More important is optical clarity and aperture. If you really want magnifying power, you will need more aperture since they are linearly related (google Dawes Limit). Remember this rule of thumb: 50x per inch of aperture.
    • Plan your star gazing nights. Have a list of objectives for each night you go out. Know what's in the sky that night and what you want to look at. Don't simply set up the scope and "surf the sky".
    • Log your observations in a notebook. This will help you become a better observer.
    1. Re:Advice from a (sort of) newbie astronomer by amstrad · · Score: 2, Informative

      Of course you should always buy as much aperture as you can afford, but your aperture budget shouldn't cut into your accessories budget. What I was really saying was: if you are torn between two scopes of the same aperture, buy the cheaper one (i.e. buy a Dobsonian over a Mak)

      However, if you look at planets or the moon, a small aperture high focal length scope is better than the opposite. I moved to urban sprawl, so I can't view deep sky stuff. My 8" Newt is mostly useless. If I could, I'd trade it in for a good 4" high focal length refractor.

  4. Re:DSP? by ChaoticLimbs · · Score: 5, Informative

    The reason you can't do this is because the purpose of the telescope is light amplification and magnification. The magnification could maybe work without adaptive optics, but if the light from the object does not get intensified by the large amount of reflector area applied, then you end up with dim images. It's also difficult to get sharp images with DSP as the light coming in contains more information than the sensor can send to the DSP. If the DSP instead applies corrective measures to the optics, you capture the image on the CCD better than if you applied it to only the data. It's a matter of losing the data which is NOT gathered by the CCD as a result of atmospheric distortion which prevents such an approach.

  5. Re:iTWire Strikes Again by Ohreally_factor · · Score: 3, Informative

    If one wanted to be pedantic, one could point out that there are other, non-optical (i.e., radio) telescopes that are much larger.

    --
    It's not offtopic, dumbass. It's orthogonal.
  6. Re:why Gran Canaria over Tenerife? by gsliepen · · Score: 3, Informative

    Sure, Tenerife's highest point is higher, but you're not allowed to build anything on the top of the Teide. The current observatories on Tenerife are approximately at the same height as those on La Palma. Yes, the vulcanoes on La Palma are still "active", but it's very benign activity, a little flow of lava once in a few decades. Those vulcanoes are also to the south of the island, while the observatories are closer to the north. The seeing quality at both sites is comparable I think.