Projection of the positions of the pole of rotation in the ICRF plane inferred by Thomas et al. (2005), red line; Carry et al. (2008), blue dotted line; Drummond & Christou (2008), green shaded line, from space telescope and ground-based measurements. The black dot represents the position of the orbital pole (Giorgini et al. 1996). The cross represents the mean intersection of the three measurements and the ellipses the uncertainties.