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    Re: A Jupiter Puzzle
    From: Marcel Tschudin
    Date: 2011 Oct 14, 01:00 +0300
    Frank,

    Thank you for your considerations.

    Yes, I see now the missing information for finding the location. The image looks about the same for all locations on the globe. Parallax which could contain such an information is very small. I would not be surprised if he indeed would try to "test" the members of NavList with such photos from Jupiter and his moons as you suggested.

    Marcel





    On Fri, Oct 14, 2011 at 12:28 AM, Frank Reed <FrankReed@historicalatlas.com> wrote:

    Marcel,

    The moons are as follows:
    -Ganymede, alone on the left.
    -Then Io and Europa. Io starts out closer to Jupiter, passes under Europa in the middle image, and ends farther from Jupiter in the third photo.
    -Finally, Callisto on the right.

    Estimated GMT (UT) of the images just by eyeball from a simulation are: 22:08, 22:50, 23:33 on October 8. The times listed on the files are 00:30, 01:12, 01:54 which with a 2 hour time zone offset would correspond to UT of 22:30, 23:12, 23:54. The differences are +22, +22, and +21 minutes. So I would say that the time on his camera was about 21.7 +/-0.5 minutes fast. Or my simulations are 21.7 minutes off, but it's nice to see that the offsets are so consistent!

    As for position determination, clearly just from casual comparisons, we can get the GMT accurate to about a minute from these images. By a bit more careful measurement and averaging four, we could probably reduce that to fifteen seconds. That would yield the longitude accurate to about 4 minutes of arc. Pretty good, right? But there's not enough information to continue. We need some observation for the local time, like the altitude of Jupiter above the horizon or a photograph looking directly at the zenith with a time stamp on it that's tied to the Jupiter images.

    -FER

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