β Pic planetary system: absolute astrometry, radial velocities, and relative astrometry observations. Absolute astrometry is showed in the upper panel as deviation from position RA = 5:47:17.08346 Dec = −51:04:00.1699 at year 1991.25, with a proper motion as in Table 3. Because individual measurements of HIPPARCOS data are 1 dimension only, they are projected in this display along the axis of the β Pictoris system, ie. 31.8 deg. Radial velocity in the second panel includes the v₀ term of −23.09 m s⁻¹ (dotted line). Two lower panels: orbital motion of the planets with respect to the star, also projected on an axis inclined by 31.8 deg to the east of the north.