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Thread: Dual Shadow Transits Across Jupiter - 2021 NOV 23

  1. #1
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    Smile Dual Shadow Transits Across Jupiter - 2021 NOV 23

    The shadows of the Galilean satellites #3 Ganymede and #4 Callisto will be simultaneously transiting Jupiter during the evening of 2021 NOV 23 for observers in the Americas.

    Photos and descriptions of the transits would be welcome additions to this thread.

    My related data and graphics can be found at https://www.CurtRenz.com/jupiter.html
    Last edited by Centaur; 2021-Nov-21 at 09:16 PM.
    For astronomical graphics and data visit
    https://www.CurtRenz.com/astronomy.html

  2. #2
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    And what power telescope would one need to view this?

  3. #3
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    I've observed transits of Jupiter with my ETX-90 using a 26 mm eyepiece, or 48x for that telescope.

  4. #4
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    Quote Originally Posted by Torsten View Post
    I've observed transits of Jupiter with my ETX-90 using a 26 mm eyepiece, or 48x for that telescope.
    That does not compute.
    https://www.highpointscientific.com/...diostar-205004

    ETA:
    Nowhere on that sheet does it indicate any x.

  5. #5
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    I calculated it as:

    Magnification = focal length objective / focal length eyepiece

    1250 mm / 26 mm = 48

    It's also listed in the fifth bullet on that page. The focal length of the scope can be found by scrolling down the page and opening up "Specification".

  6. #6
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    Quote Originally Posted by Torsten View Post
    I calculated it as:

    Magnification = focal length objective / focal length eyepiece

    1250 mm / 26 mm = 48

    It's also listed in the fifth bullet on that page. The focal length of the scope can be found by scrolling down the page and opening up "Specification".
    That explains it for NOB. Thanks
    I'm curious about how "large" is the planet using it. I had a friend about 40 years ago bought a telescope and showed me Jupiter, but it seemed to be the size of a marble and I couldn't make out any features. I don't remember the magnification of it sorry.

  7. #7
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    It appears very small in my scope with that eyepiece. I also have the 9.7 mm eyepiece, yielding 129x, but I've never enjoyed using it due to its short eye relief.

    I haven't had a really good view of Jupiter in some time. The last time I looked was during its conjunction with Saturn last year. The pair was low in the sky and the relatively poor seeing wasn't helped by the inadequate time I allowed the scope to cool down. Between those two issues and my worsening eyesight I could barely make out the cloud bands.

    It's forecast to be cloudy and possibly snowing here for this double transit, so I'll likely miss out on this treat.

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    If it that "small" how could you detect the moon(s) shadow across the face?

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    Quote Originally Posted by bknight View Post
    If it that "small" how could you detect the moon(s) shadow across the face?
    Even though Jupiter appears small in the eyepiece, in good seeing conditions the shadows are distinct dots. Try opening the image in the link below and adjusting its size until the planet appears to be about 5 mm in diameter (using the [Ctrl][-] key combination should do it for a desktop browser). That's about what to expect with that small scope, and to me that's amazing.

    https://scx1.b-cdn.net/csz/news/800/...ubleshadow.jpg

  10. #10
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    Quote Originally Posted by Torsten View Post
    Even though Jupiter appears small in the eyepiece, in good seeing conditions the shadows are distinct dots. Try opening the image in the link below and adjusting its size until the planet appears to be about 5 mm in diameter (using the [Ctrl][-] key combination should do it for a desktop browser). That's about what to expect with that small scope, and to me that's amazing.

    https://scx1.b-cdn.net/csz/news/800/...ubleshadow.jpg
    I got it about 7mm and your eyes are way better than mine. I gain a dot at about 12mm.
    Thanks

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