Recently I started to imported actual ISS, HST and Tiangong Orbital-Data from (www.heavens-above.com and http://www.celestrak.com) via conversed "Two Line Elements" (TLE). I do this with the "Scenario Editor TLE"-Addon ([ame="http://www.orbithangar.com/searchid.php?ID=2617"]http://www.orbithangar.com/searchid.php?ID=2617[/ame]).
Today i wondered, why there is a certain difference between the ISS's position shown in orbiters map MFD and online visualisation applets in the internet or my heavens above app on my android tablet. I always thought its a calculation error somehow in the conversion formula from TLE to the orbiter format. Then just by accident i saw, that the UTC time differs by exactly 1 minute and 6 seconds from my internet-synchronised pc clock. When i manually set the time in the scenario editor the position of the ISS is (almost) perfect.
How does this come? Does this difference to the PC-clock has a special background? Somewhere i read orbiter uses a special time (Dynamical Barycentric Time) which is "not the same but similar" to UTC. Before orbiter i never heard of that time before, but after i read about it in wikipedia i understood the necessity. But is that especially this time difference? As i understood this Barycentric Time there must be a difference of about 8 minutes to the barycenter?
Today i wondered, why there is a certain difference between the ISS's position shown in orbiters map MFD and online visualisation applets in the internet or my heavens above app on my android tablet. I always thought its a calculation error somehow in the conversion formula from TLE to the orbiter format. Then just by accident i saw, that the UTC time differs by exactly 1 minute and 6 seconds from my internet-synchronised pc clock. When i manually set the time in the scenario editor the position of the ISS is (almost) perfect.
How does this come? Does this difference to the PC-clock has a special background? Somewhere i read orbiter uses a special time (Dynamical Barycentric Time) which is "not the same but similar" to UTC. Before orbiter i never heard of that time before, but after i read about it in wikipedia i understood the necessity. But is that especially this time difference? As i understood this Barycentric Time there must be a difference of about 8 minutes to the barycenter?
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