  V4334 Sgr (a.k.a. Sakurai's object) is the central star of an old planetary
nebula that underwent a very late thermal pulse a few years before its
discovery in 1996. We have been monitoring the evolution of the optical
emission line spectrum since 2001. The goal is to improve the evolutionary
models by constraining them with the temporal evolution of the central star
temperature. In addition the high resolution spectral observations obtained by
X-shooter and ALMA show the temporal evolution of the different morphological
components.
