Some of the individual pixel spectra of [Ca ii] lines are shown. The left panel shows the spectra from 2010, and the right panel shows the spectra taken in 2012, position 2. Pixel 00 (2010) corresponds to the south-east position. Pixel 00 for position 2 in 2012 is located in the east. Since the [Ca ii] lines are located in a region which is dominated by atmospheric absorption lines, it is hard to determine whether the substructure seen on the [Ca ii] lines is intrinsic. The bottom-most panel gives the residuals of the slit spectrum in 2012 (position 2) when the spectrum at +0.6′′ (pixel 30) is subtracted from the spectrum at −2.5′′ (pixel 15) distance to the central star. Negative distances indicate directions in the south-(east) of the nebula. Positive distances indicate directions towards the north-(west).