# How can I calculate Mean anomaly from True longitude?

So, I have

- TLE data
- Reference frame: QMOD
- Type: Osculating
- Semimajor axis
- Eccentricity
- Asceding node
- Argument of Perigee
- True longitude

I must calculate Mean Anomaly, just I need formula

• I think it would be better if you explained more what you are trying to do. Mixing a TLE and osculating elements doesn't make sense. Why don't you actually show, or explain what you have more clearly. – uhoh Jul 17 '18 at 7:35
• @uhoh I have TLE data and reference frame. Just I need formula for converting from true longitude to mean anomaly – iLLkeeN Nemo Jul 17 '18 at 7:56
• You have TLE? But TLE entry of line 2 columns 44–51 is the value of mean anomaly, in degrees! – SF. Jul 17 '18 at 12:32
• There are a lot of questions like this, and I think someone should do a definitive 'elliptical orbit' answer, explaining how to compute values, talking about things like the Equation of the Center, and so on. Or maybe just link to a good resource, something like stargazing.net/kepler/ellipse.html – user7073 Jul 17 '18 at 15:11
• @iLLkeeNNemo: cat tle | tail -n +1 | head -n 1 | cut -c 44-51 ? How does one write a formula for a given? – SF. Jul 18 '18 at 5:53