Schematic of the rotation axis angles for a globular cluster with an inclined plane. The light grey plane shows a face-on cluster with position vectors in the plane of the sky: RA, Dec, and the line-of- sight (LOS) vector towards or away from the observer. In dark grey is an inclined plane, with projected position vectors and a rotation axis described by two angles with respect to the face-on cluster: position angle of the rotation axis θ₀ and inclination angle i.