tleread() loading incorrect data

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am 2024-8-8

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https://ww2.mathworks.cn/matlabcentral/answers/2144004-tleread-loading-incorrect-data

编辑： Kurt 2024-9-20，17:55

Hello,

I'm trying to load TLE data to MATLAB using tleread function. Examining the MeanMotion values, they seem to either be loaded incorrectly or some conversion is going on. I tried to look in the help files for the tleread but couldn't find any details.

For instance, this is the tle data for the Iridium constellation: https://celestrak.org/NORAD/elements/gp.php?GROUP=iridium&FORMAT=tle

When saved as a .tle file and loaded to MATLAB, the MeanMotion values are incorrect.

I'm using MATLAB online, so version R2024a. I also tried it on a locally installed MATLAB (2024a), and getting the same results.

Am I missing something?

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am 2024-8-8

Thank you for your reply! I have just submitted a bug report.

Kurt 2024-9-20，15:29

编辑：Kurt 2024-9-20，17:55

I ran into this too. Apparently Matlab is converting Mean Motion to orbits per second, not orbits per day. The conversion factor is 0.0041667 which equals 360/86400. It took me a while to track down this magic number.

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采纳的回答

Gayathri 2024-8-9

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https://ww2.mathworks.cn/matlabcentral/answers/2144004-tleread-loading-incorrect-data#answer_1496819

Hi @am,

The TLE data contains “mean motion” in revolutions/day unit. The “tleread” function in MATLAB reads the “mean motion” in degree/second unit. Hence the change in values is observed.

1 revolution/day = (360/(24*60*60)) degree/second

Hence, all the mean motion values in original TLE data are divided by 240 and this is the value seen in the data read by “tleread” function.

E.g. The first “mean motion” value 14.35329424426931 rev/day is converted to (14.35329424426931/240) degree/second = 0.0598 degree/second.

Hope you find this information helpful.