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Thread: High Magnification Footage of the International Space Station

  1. #1
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    High Magnification Footage of the International Space Station

    This morning I had an 89 degree high pass in perfectly clear weather just after a cold front moved through the area. Seeing was pretty turbulent but the transparency couldn't be beat. I tracked ISS right up to the zenith using my custom software for closed-loop optical guidance.

    https://github.com/AstronomyLiveYt/SatTraker

    I'm also currently testing and patching ASCOM compatibility using a smaller NexStar SE scope and it seems to be going well so far, but I still need to do a field test on a real sat with that scope.

  2. #2
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    Wow. Some of the individual frames are really remarkably clear.
    At night the stars put on a show for free (Carole King)

    All moderation in purple - The rules

  3. #3
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    Just came across this post - that's an outstanding piece of work. Congratulations!

  4. #4
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    Quote Originally Posted by AGN Fuel View Post
    Just came across this post - that's an outstanding piece of work. Congratulations!
    Thanks! I'm still working on the software but ran into a major hiccup with my laptop. Something's gone wrong and now my software can't access most cameras. I'm pretty sure it's a problem with the laptop itself though, it's generating some errors with amcap as well, but even some of the cameras amcap can still access seem to be offline to my program. It's like something's getting in the way between my software and the hardware and it may be related to a failure of the laptop's built-in webcam hardware.

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    What caused the blurry images at the beginning? Is the camera "finding" the proper settings? I'll second the congratulations.

  6. #6
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    Fantastic work! Man that is rock solid! (All 7 pics below are of the identical patch of the image. If there's any drift, it's less than a pixel...)

    Question: is it rotating in the shot along its long axis or around the vertical axis?

    When I went back and skipped through it, it seems to change shape much more than expected - presumably fore-shortening as it crosses the sky, but its seems strange.

    Look how the panels seem to get much shorter, yet they don't seem to be rotating about the long axis - they seem to stay vertically oriented in the frame.


    ISS.png
    Last edited by DaveC426913; 2018-Dec-08 at 12:01 AM.

  7. #7
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    Quote Originally Posted by bknight View Post
    What caused the blurry images at the beginning? Is the camera "finding" the proper settings? I'll second the congratulations.
    I was manually refocusing the telescope. Mirror flop is an issue with my Schmidt-Cassegrain and this corresponds with a loss of focus as the tube moves over a large portion of the sky. Fortunately I was able to let the program do its thing completely hands-free once I locked onto ISS. I focused all of my attention on the focus knob (no pun intended) and tried to get it dialed in as accurately as possible early in the pass.

  8. #8
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    Quote Originally Posted by DaveC426913 View Post
    Fantastic work! Man that is rock solid! (All 7 pics below are of the identical patch of the image. If there's any drift, it's less than a pixel...)

    Question: is it rotating in the shot along its long axis or around the vertical axis?

    When I went back and skipped through it, it seems to change shape much more than expected - presumably fore-shortening as it crosses the sky, but its seems strange.

    Look how the panels seem to get much shorter, yet they don't seem to be rotating about the long axis - they seem to stay vertically oriented in the frame.


    ISS.png
    Not sure how best to describe it. Take a look at this diagram:
    https://qph.fs.quoracdn.net/main-qim...46b2fc3a2509-c
    When ISS is directly overhead, I'm looking at ISS up the Z Axis. The solar panels are not oriented the way they are in this diagram; they're actually close to 90 degrees different from this with their long axis roughly pointed down the Z Axis. When ISS is directly overhead for me, the sun is just below the horizon in the pre-dawn hour and therefore to point at the sun the panels long axis is pointed roughly perpendicular to earth's surface. The panels rotate to track the sun while ISS maintains its normal LVLH orientation with the Z axis pointed perpendicular to the ground below and the X axis facing the direction of its orbit around the earth (https://spaceflight.nasa.gov/feedbac..._15_11_76.html ). As ISS is rising the X axis is aimed my way (roughly) and the habitat sections that run down the X axis are foreshortened. As ISS approaches the zenith, I'm looking up the Z axis and the solar arrays are foreshortened.

  9. #9
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    Quote Originally Posted by NGCHunter View Post
    Not sure how best to describe it. Take a look at this diagram:
    https://qph.fs.quoracdn.net/main-qim...46b2fc3a2509-c
    When ISS is directly overhead, I'm looking at ISS up the Z Axis. The solar panels are not oriented the way they are in this diagram; they're actually close to 90 degrees different from this with their long axis roughly pointed down the Z Axis. When ISS is directly overhead for me, the sun is just below the horizon in the pre-dawn hour and therefore to point at the sun the panels long axis is pointed roughly perpendicular to earth's surface. The panels rotate to track the sun while ISS maintains its normal LVLH orientation with the Z axis pointed perpendicular to the ground below and the X axis facing the direction of its orbit around the earth (https://spaceflight.nasa.gov/feedbac..._15_11_76.html ). As ISS is rising the X axis is aimed my way (roughly) and the habitat sections that run down the X axis are foreshortened. As ISS approaches the zenith, I'm looking up the Z axis and the solar arrays are foreshortened.
    What's weird though is that the panels don't seem to rotate more than 20 degrees or so, so it's not like we were looking along their length at the start and they get foreshortened to half their length as they rotate.

    I don't see how they can appear to get 50% shorter without a much more dramatic foreshortening than that caused by a 20% pitch.
    See here:
    ISS2.jpg
    Last edited by DaveC426913; 2018-Dec-11 at 01:07 AM.

  10. #10
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    Quote Originally Posted by DaveC426913 View Post
    What's weird though is that the panels don't seem to rotate more than 20 degrees or so, so it's not like we were looking along their length at the start and they get foreshortened to half their length as they rotate.

    I don't see how they can appear to get 50% shorter without a much more dramatic foreshortening than that caused by a 20% pitch.
    See here:
    ISS2.jpg
    I might not be explaining it well, but it should be much more than a 20% change in perspective from the time the station rises to the time it's near the zenith. Think of it like this, for an early morning pass headed up to the zenith, the sun is more or less opposite the station in the sky as it rises in the west (very roughly, hence the rotation of the panels around the Z axis which I'm not really talking about here). Therefore the panels should look more or less face-on to the telescope as the station rises over the horizon. As it approaches the zenith the panels should remain face-on to the sun, but since the sun is just below the eastern horizon, that means an observer directly below the station looking up should be looking nearly edge-on to the solar panels. Foreshortening of the panels should be at its greatest extent near the zenith. Your red line seems to denote the angle of the panel's rotation around the Z axis, but my understanding is that the panels also rotate around the Y axis in that diagram in order to track the sun as the station maintains a fixed LVLH attitude with the Z axis aimed perpendicular to the ground below.

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