RE: North Korea satellite: retrograde ground track displayed in launch control centre

From: Ted Molczan (
Date: Wed Apr 11 2012 - 21:11:05 UTC

  • Next message: Jonathan McDowell: "Re: North Korea satellite: retrograde ground track displayed in launch"

    Bob Christy wrote:
    > The image displayed on the LCC screen is not a ground track - the line
    > is an orbit in a representative 3D view. The website that displayed the
    > video cut off the top of the image with a message box when I paused the
    > it for the screen capture. The full view of the north pole showed the
    > orbit rising and disappearing over the Earth's limb in a similar way to
    > the Orbit Architect view.
    Thank you, Bob! I was aware that it was 3D representation and pointed that out in my post last night, but failed to
    grasp the implication for interpreting the image.
    > If the LCC image seen in animated mode, I suspect the satellite will
    > move around the ellipse, and the Earth will rotate underneath it. The
    > Korean software and Orbit Architect seem to display in the same mode.
    Yup. This means that the typo hypothesis can be discarded, and although it is true that the Earth did not rotate in the
    scene captured from the video of the LCC display, it was not due to an error in the software or its configuration, but
    simply because it was a representation of the orbit relative the Earth at an instant of time. Thankfully, there is no
    need to be concerned about the NOTAMs.
    It also means that my 97.45 deg orbit estimate probably is close, but could be out a bit in RAAN:
    1 79802U          12103.11415512  .00000000  00000-0  00000-0 0    06
    2 79802  97.4500 182.0500 0002000 359.9726 179.8827 15.21000000    03
    Off-list, in response to my query, you mentioned that for the 97.4 deg inclination, and launch on Apr 11 at 22:00 UTC,
    you had RAAN 113.4 deg. Rotating that to the epoch of the above TLE yields 184.7 deg. Can we rely on that?
    Ted Molczan
    Seesat-l mailing list

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