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    Re: Position fix by satellite
    From: Greg Rudzinski
    Date: 2014 Jun 25, 08:14 -0700


    What is given for the ISS on various web sights is the geographic position and altitude for any UT time. I got an ISS GP Lat 51.659° N ; Lon 4.069° W at an altitude of 225.78 nautical miles for 6/23/2014 16:15:29 UT. Then the Sun's Hc altitude and azimuth can be worked up using the GP as the assumed position ( Hc 37° 4.38' Az 261.2°). This should be enough information to get a position with a known Earth radius. The position error will be +/- 16' semi diameter of the Sun. There is another less accurate way to get a rough position and that is to measure the width of ISS in pixels ( 11px ) vs. known length ( 109 meters ) and then use the Sun as a yard stick ( 547px ) with a solar diameter of 31.47167' for the day of the image. This will give an approximate line of sight distance from the photographer to the ISS setting up a long distance piloting problem.

    I have a hunch Frank has an easier way to do this though.

    Greg Rudzinski


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