Figure 4: Geometric definitions for the precessional motion of spinning compact binaries [54, 306].
We show (i) the source frame defined by the fixed orthonormal basis ; (ii) the instantaneous
orbital plane which is described by the orthonormal basis ; (iii) the moving triad
and the associated three Euler angles , and ; (v) the direction of the total
angular momentum which coincides with the –direction. Dashed lines show projections into
the – plane.