R Cas H₂O-maser light curve 1987-1999 displayed in integrated fluxes vs. TJD. The red squares denote detections; the black circles denote non detections; downward arrows indicate upper limits in those cases. The drawn curve shows a damped oscillator fitted to the data and has a period of 430 ± 4 days, very similar to the stellar period of visual variation, the location of the maxima of which are indicated by the dotted vertical lines (visual magnitudes; AAVSO-data).