Re: ISS Transit prediction problems?

From: Thomas Fly (
Date: Sun Aug 31 2003 - 10:22:08 EDT

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    Björn Gimle wrote:
    > Rob's SkyMap has had solar transit predictions since version 5.1
    I experimented with it, after reverting a Windows Me laptop to a whiney old
    Windows 98 disk... I've subsequently learned that it's possible to run SkyMap on
    Windows XP, so maybe soon I can give it another try.
    Kevin Fetter used Rob's Earth.exe program, as well as STK 4, to check a solar
    transit photographed by Torsten Edelmann a while back:
    I analyzed the photo & determined that my centerline was about 250 meters
    northwest of the actual track.  Kevin's results, using the nearest OIG TLE, were
    dead-on with Earth, and maybe 25 meters southeast with STK... however, I later
    thought that quite likely Kevin didn't factor in Torsten's elevation of 630
    meters- since I forgot to tell him what the elevation was- which would have
    pushed the centerline about 125 meters to the southeast, for that transit.
    The ISS's solar panels are 73 meters wide, and the earth is about 8000 miles /
    13000 km. in diameter, so at some point, reducing errors becomes difficult
    indeed.  Obviously, predictions can be only as good as the TLE you base them on,
    and I don't have a good feel for what kind of TLE errors are typical for the
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