Keywords: Position Angle - Spherical Triangle for Derivation.svg en Diagram showing the spherical triangle used for deriving the formula for the astronomical position angle of point 1 with respect to point 2 The corners of the triangle are the north celestial pole N point 1 with celestial coordinates alpha1 and delta1 and point 2 with celestial coordinates alpha2 and delta2 The angle P at point 2 is the position angle of point 1 with respect to point 2 A formula for P can be derived applying spherical trigonometry to this triangle own Sch 2011-09-16 Cc-zero Astronomical diagrams |