Problem How to orient a planet

[cristiapi]

I'm trying to correctly orient some planets, in particular Pluto-Charon.
I mean that I'm trying to put the prime meridian in the correct position at any given time.

In the configuration files I see the parameters SidRotOffset, Obliquity, LAN, ... but I don't understand how they work.

Please, could somebody explain how to do that?

Thank you
Cristiano

 

[Interstellar Planet]

Obliquity is the tilt of the planet relative to the reference plane.

SidRotOffset is how rotated the planet is at the time specified in the "Epoch" entry

LAN is a bit more complicated. Imagine the planet's equatorial plane and the reference plane. If the planet is tilted, the two planes will intersect at a line. LAN is the rotation of this line on the reference plane.


First of all, did you define Charon's orbit relative to the ecliptic or Pluto's equator? Do you mind posting what you have so far?

 

[Shifty]

Does Piper's Pluto and Moons pack have the wrong orientation?

 

[Interstellar Planet]

Does Piper's Pluto and Moons pack have the wrong orientation?

It has the correct orientation. I'm pretty sure that cristiapi is trying to make his own model of Pluto and Charon.

 

[cristiapi]

Obliquity is the tilt of the planet relative to the reference plane.

SidRotOffset is how rotated the planet is at the time specified in the "Epoch" entry

LAN is a bit more complicated. Imagine the planet's equatorial plane and the reference plane. If the planet is tilted, the two planes will intersect at a line. LAN is the rotation of this line on the reference plane.

Good! LAN is the key parameter for my problem.
In this very moment, I'm using the LAN that I found in the Piper's Pluto and Moons pack and my simulation is much, much better.

First of all, did you define Charon's orbit relative to the ecliptic or Pluto's equator?

I'm writing a DLL to accurately simulate the motion of the 6 bodies in the Pluto system.
I just calculate the barycentric ecliptic coordinates J2000 using a Runge-Kutta integrator of order 8.

Do you mind posting what you have so far?

Not much to post:

In the Charon.cfg file:
SidRotPeriod = 551856.70656000 ; sec (6.3872304 days)
SidRotOffset = 5.22884936 ; rad. pi + PLUTO_SidRotOffset
Obliquity = 1.97 ; rad. (112.872427 deg media 2000-2050)
LAN = 0.7512944298135 ; rad - same as Pluto

Pluto.cfg:
SidRotPeriod = 551856.70656000 ; sec (6.3872304 days)
Obliquity = 1.97 ; rad (112.872427 deg media 2000-2050)
SidRotOffset = 2.087256706 ; rad. CHARON_SidRotOffset - pi
LAN = 0.7512944298135 ; rad (43.046 deg, or 223.046-180deg)

I need to play with the LAN parameter.

Thank you
Cristiano

---------- Post added at 17:12 ---------- Previous post was at 17:08 ----------

Does Piper's Pluto and Moons pack have the wrong orientation?

Seems wrong to me. Using the "Coordinate axes" display, I see that the Pluto x axis doesn't point toward Charon (and the same happens for Charon). But could be a problem that I get because I use my own modules (DLL's).

Cristiano

---------- Post added at 17:30 ---------- Previous post was at 17:12 ----------

In an attachment found in the thread posted by Shifty, there are several cfg files where I see:

; === Configuration file for Pluto ===
; === Add-on configuration by Joseph Morgan ===
Name = Pluto
Module = spice
Kernel = Kernels\plu017.bsp
Body = PLUTO
Origin = SUN
ParentBarycenter = SSB


Please, could somebody tell me whether Orbiter supports the NAIF files?

Thank you
Cristiano