Abstract:
The O-C curve of SW Cyg between 1880 and 1977 is presented and discussed. It is found that the orbital period undergoes a systematic change, becoming greater with time. In addition, a periodic oscillation of amplitude 0ᵈ.015 with period of 43.8 years is superimposed on this general trend. It is concluded that the increase int he period is due to a transfer of mass from the secondary star to the primary and the periodic oscillation is due to the light time effect of the third body of mass function f(m) = 0.006M☉.
