Reply To: Thermal Desktop Orbital Elements Reference Frame

[Doug Bell]

Thermal Desktop computes the beta angle from a series of transformation matrices calculated to relate the orbital coordinate system to a celestial coordinate system. They are the matrices used for graphics display and for computing the solar vectors in the vehicle coordinate system. Embedded in the process is the same equation for beta angle you cited.

The difference is the declination formula. We use ecliptic longitude (measured in the ecliptic plane) instead of right ascension (measured in the equitorial plane).