#### Marijn

##### Active member

Currently, the relevant part of my cfg file looks like:

; === Planetary Mean Orbits ===

Epoch = 2010.99931554

SemiMajorAxis = 168505699055.3255

Eccentricity = 2.037451084785423e-1

Inclination = 0.10532956489987094

LongAscNode = 0.03596892030325171

LongPerihelion = 1.191779504398578

MeanLongitude = 2.9668482563280243

When I select this body as a target in Orbiter's Orbit MFD, the shape and orientation of the orbit looks good to me. Except for the current position of the body in the orbit. That one is clearly wrong. I expect that there is a mistake in the calculation of the MeanLongitude. But I don't understand why.

Page 142 of the Orbiter Manual says:

Mean Longitude = Mean anomaly(ma) + Longitude of the periapsis.

Also, Longitude of the periapsis = Longitude of the ascending node(om) + Argument of periapsis(w).

When I do this math and convert it to radians, I end up with the 2.96 value above which must be incorrect. I got the epoch using the Orbiter Date utility.

Anybody who can help me to get it right?

The data I am working with:

[{

"epoch": 2455562.5,

"a": 1.126391025934071,

"e": 0.2037451084785423,

"i": 6.034939533607825,

"om": 2.060867329373625,

"w": 66.22306846088361,

"ma": 101.7039479473255

}]

Thanks