SYNCHRONISED DOME ROTATION - Brayebrook Observatory

SETTING UP THE EQUATIONS (cont.)Referring to VIEW FROM SOUTH. Assume you are looking up the polar axis towards the north celestial pole P*. The point of m along theellipse’s circumference can be used to define Z’ :-hence( X − X' ) 2r 2+( Z' −Z) 2rcosφ( ) 2 =1but X − X' = rsin H where H is the hour angle( rsin H) 2+ Z'−Zr 2 rcosφ( )2from which( ) 2 =1( )( )Z' = Z + r cosφ 1− sin 2 Hhence Z' = Z + r cosφ cos 2 HhenceZ' = Z + r cosφ cos HWe now have all the equations needed to establish the primary coordinates X’,Y’,Z’, from the telescope’s hour angle.when the cg lies on the optical axisX'= X + rsin HY'= Y − rsinφ cosHZ' = Z + r cosφ cos HX'= XY'= YZ' = Zwhen the polar axis lies on the dome north-south centreline X = 07