;MAIN COORDINATES
;x-east in the imageplane,y-north,z-toward the spacecraft

; equat_coord
;x==x, y,z- toward the spacecraft

x_equat_norm=float([1,0,0])
y_equat_norm=crossp(norm_ring_plane,x_equat_norm)
if (y_equat_norm(2) le 0) then y_equat_norm=y_equat_norm*(-1)