M Twice or more maximum or minimum peaks are observed. SR Twice or more maximum or minimum peaks are observed. E Twice or more short-period fading are observed. S Some brightening or fading phases in short time are observed. L Twice or more maximum or minimum peaks are observed.
Period is irregular.
Only few observations. In case of unfiltered CCD images, the threshold is 2.0 mag. Here is an example of the three steps of slow variability . In addition, a star whose spectrum is M, C or S, or a star identied with 2MAS data, is judged as a red variable star. If twice or more maximum or minimum peaks are observed, the period is recorded.