Light Variations of the Anomalous Central Star of Planetary Nebula Sh   2-71
  We present an analysis of light variations in UBVRI of the anomalous object in the center of planetary nebula Sh 2-71. We refined the linear ephemeris of the light maxima to JD{max} = 2449862.0 + 68.101 (E-96), but also identified long-term, obviously non-periodic variations. The latter manifest themselves in large O-C shifts, a variable profile of light curves (hereafter LC) and changes in the mean brightness of the object. Our spectroscopic observations suggested the presence of a superdense nebula in the center of Sh 2-71. 
Zdenek Mikulasek, Augustin Skopal, Miloslav Zejda, Ondrej Pejcha,   Lubos Kohoutek, David Motl, A. A. Vittone, L. Errico