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Top 5 largest optical telescopes in operation

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The 5 largest optical telescopes in operation by effective mirror aperture: Large Binocular Telescope (Arizona, USA), and more.

Snapshot · 2026-09-01

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  1. 1

    Large Binocular Telescope (Arizona, USA)

    11.9 m combined

  2. 2

    Gran Telescopio Canarias (Canary Islands, Spain)

    10.4 m

  3. 3

    Hobby-Eberly Telescope (Texas, USA)

    10.0 m effective

  4. 4

    Keck 1 (Hawaii, USA)

    10.0 m

  5. 5

    Keck 2 (Hawaii, USA)

    10.0 m