Table 4: The periods found from the period analysis of the mean V magnitude and the peak-to-peak V amplitude variations between different observing seasons. The periods on the left are those found by the method of Horne & Baliunas (1986), and on the right are the periods found by PDM (Stellingwerf 1978).

HB		PDM
Mean	Amplitude	Mean	Amplitude
24.6 yr	-	24.4 yr	27.0 yr
-	13.0 yr	-	11.4 yr