Moon orientation parameters

For any CelestialBody, the frame obtained through the method getBodyOrientedFrame() uses the IAUPole model provided by the IAU - WGCCRE, and implemented in “PredefinedIAUPoles”

However, for the specific case of the Moon, the JPL ephemerides (DE4xx) contain also these parameters (with a much better accuracy I think), but they are not used in Orekit. Even if Orekit reads these files, they are used only the position-velocity, not for the body orientation.

Has someone ever implemented the reading these parameters and the computation of euler angles phi, theta, psi from Chebishev polynomials ?

As far as I know, there have been no attempts to do that.
It would be worth having this feature available, though.

Thanks for your answer Luc, I also think it would be interesting to have this feature. The current IAU Pole accuracy (<0.1° on Euler angles) is enough for mission design and analysis, but not for flight dynamics operations and “precise” orbit determination.

Just to add some words on this subject. As Sebastien said, the common Orekit user could think that the JPL ephemerides are used to compute the Moon libration angles as the ephemerides are loaded and there is no way to know (except by diving into the source code) that this is the IAU analytical model that is used instead. Could be nice to add a little comment in the getBodyFrame and getInertiallyOrientedFrame methods to explain that these frames are computed using the IAU recommandation with the reference of the paper. It would avoid any misinterpretation (for Earth’s Moon only), in my opinion.