<p>I have a bunch of orbital elements (inclination, longitude of the ascending node, mean anomaly, argument of periapsis) that are all referenced from an equatorial reference frame. But the program I am trying to use requires the orbital elements in an <em>ecliptic</em> frame. Is there an easy/convenient way to convert between the two frames?</p>
<p>I also have the RA and Dec for the orbit pole, also in the equatorial frame. I am aware of some rotation matrices that allow me to convert between equatorial and ecliptic frames—should I just apply the matrix to the RA and Dec of the orbit pole? Is there a way to turn that into orbital elements?</p>
<p>Or should I turn the equatorial elements into a state vector (Cartesian position and velocity) and then apply the matrix to <em>that</em>, and then convert the ecliptic vector into orbital elements?</p>
<p>What is the easiest way to go about this?</p>

<orbit><orbital-elements><ecliptic><frame-of-reference>
Converting orbital elements from equatorial reference frame to ecliptic
Geroditus
# Converting orbital elements from equatorial reference frame to ecliptic

(Asked by: username_0 on 2020-07-15)

I have a bunch of orbital elements (inclination, longitude of the ascending node, mean anomaly, argument of periapsis) that are all referenced from an equatorial reference frame. But the program I am trying to use requires the orbital elements in an *ecliptic* frame. Is there an easy/convenient way to convert between the two frames?

I also have the RA and Dec for the orbit pole, also in the equatorial frame. I am aware of some rotation matrices that allow me to convert between equatorial and ecliptic frames—should I just apply the matrix to the RA and Dec of the orbit pole? Is there a way to turn that into orbital elements?

Or should I turn the equatorial elements into a state vector (Cartesian position and velocity) and then apply the matrix to *that*, and then convert the ecliptic vector into orbital elements?

What is the easiest way to go about this?

**Tags:** orbit, orbital-elements, ecliptic, frame-of-reference

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## 0 answers

