The expansion proper motions of the extraordinary giant lobes of the
  planetary nebula KjPn 8 revisited
  The primary aim is to establish a firm value for the distance to the
extraordinary planetary nebula KjPn 8. Secondary aims are to measure the ages
of the three giant lobes of this object as well as estimate the energy in the
eruption, that caused the most energetic outflow, for comparison with that of
an intermediate luminosity optical transient (ILOT). For these purposes a
mosaic of images in the Halpha+[N II] optical emission lines has been obtained
with the new Aristarchos telescope in 2011 for comparison with the images of
the KjPn 8 giant lobes present on the POSSI-R 1954 and POSSII-R 1991 plates.
Expansion proper motions of features over this 57 yr baseline in the outflows
are present. Using these, a firm distance to KjPn 8 of 1.8 +- 0.3 kpc has been
derived for now the angle of the latest outflow to the sky has been established
from HST imagery of the nebular core. Previously, the uncertain predictions of
a bow-shock model were used for this purpose. The dynamical ages of the three
separate outflows that form the giant lobes of KjPn 8 are also directly
measured as 3200, 7200 and >= 5x10^4 yr respectively which confirms their
sequential ejection. Moreover, the kinetic energy of the youngest and most
energetic of these is measured as ~10^47 erg which is compatible with an ILOT
origin.
