Photoelectric observations of CH Cygni during the explosive phases of 1967–68

Observations made at Trieste in 1967 and 1968 of CH Cygni reveal a strong variability, particularly in U colour. From the observed colours, a suggestion is made about the existence of a hot companion which could be a subdwarf.Presented at the Trieste Colloquium on Mass Loss from Stars, September 12–16, 1968.