  CK Vulpeculae, which erupted in AD 1670-71, was long considered to be a nova
outburst; however, recent observations have required that alternative scenarios
be considered. Long slit infrared spectroscopy of a forbidden line of iron
reported here has revealed high line-of-sight velocities
($\sim\pm900$~km~s$^{-1}$) of the ansae at the tips of the bipolar lobes imaged
in H$\alpha$ in 2010. The deprojected velocities of the tips are approximately
$\pm2130$~km~s$^{-1}$ assuming the previously derived inclination angle of
$65^\circ$ for the axis of cylindrical symmetry of the bipolar nebula. Such
high velocities are in stark contrast to previous reports of much lower
expansion velocities in CK~Vul. Based on the deprojected velocities of the tips
and their angular expansion measured over a 10-year baseline, we derive a
revised estimate, with estimated uncertainties, of $3.2^{+0.9}_{-0.6}$~kpc for
the distance to CK~Vul. This implies that the absolute visual magnitude at the
peak of the 1670 explosion was $M_V = -12.4^{+1.3}_{-2.4}$, indicating that the
1670 event was far more luminous than previous estimates and brighter than any
classical nova or any Galactic stellar merger. We propose that CK~Vul belongs
to the class of Intermediate Luminosity Optical Transients (ILOTs), objects
which bridge the luminosity gap between novae and supernovae. While eruptions
in lower luminosity ILOTs are attributed to merger events, the origin of the
highly luminous ILOT outbursts is currently not known.
