Position-velocity diagrams of the C₄H(N = 24–23) (top) and CN (2₀₃₂−1₀₂₁)(bottom) line emission along an 1′′-wide NS slit at the right ascension of the star (09^h47^m5745). The shells in Fig. 11 where C₄H is detected appear as bright elliptical arcs. The white/black ellipse corresponds to shells of radii 17′′, 21′′, 26′′ and 31′′ centred 1′′N from the star (4′′N for the 31′′ shell) and in radial expansion at a velocity of 14.5 km s^-1. Note that the CN (2₀₃₂−1₀₂₁) line shown here is blended by two weaker hfs components, (2₀₃₂−1₀₂₂) and (2₀₃₃−1₀₂₃), respectively 11.5 and 16.3 MHz higher in frequency. Those appear on the graph as ghosts of the brightest component shifted by –15.2 and –21.6 km s^-1.