FG Sge is one of the most unique variable stars known.  Evolving as we watch, it's variations are totally unpredictable. Before 1992,  FG Sge spent many years as a magnitude 9 star before major 'dust' events began in mid 1992.  The star has also evolved and cooled from a B type star to it's present type K2 in just over a century.   It's the central star of the Planetary Nebula PK060.3-07.3.  Probably a 'born again star', the speculation as to whether FG Sge becomes hydrogen deficient in the future continues.  Last recording of the star was in 2008 at just below magnitude 17.0C