TW Vir Type: SS Cygni AAVSO lightcurve (2020 ) AAVSO lightcurve (index) SS Cygni-type variables increase in brightness by 2-6 magnitudes in V in 1-2 days and in several subsequent days return to their original brightnesses. The values of the cycle are in the range 10 days to several thousand. AAVSO Legacy Cataclysmic Variable Programme