1996A&AS..116....9S

On the basis of photometric observations published since 1974, we present new times of maximum light of the LBV η Car, and discuss the variation of the pulsation period. It is shown that -over more than two decades- the pulsation period is stable at 58.d58 with a mean error of about half an hour. η Car is the first LBV for which such a stable pulsation period can be recognised. In addition, we present evidence for the possible presence of a secondary period which beats with the main period on a time scale of the order of 20 years.