Beyond that, the fact that the 20% dimming events have only been observed by Kepler on this singular star makes it unlikely that it’s an equipment malfunction. It had been picking them up long before it was used to focus specifically on that star and continues to pick them up today. This is not likely an equipment malfunction.

So not only is it not an astrophysical phenomena, it has also not been confirmed by a second telescope although that would be easy, and there are funny coincidences with Earth’s orbital period and the telescope turning events. This is a no go to begin with.

The 100 year dimming is questionable because of the difficulties with comparing the star’s light strength between old photographic plates. Different kind of chemicals have been used over the years,being differently sensitive to different wavelengths of light. Also, the photo chemicals have degraded differently over the years. Different observatories were used, some with documented defects, others without documentation of their defects, and the weather has varied. Since the big dimmings have lasted several hours to a couple of days, a single exposure would easily reveal a 22% dimming, as well as a much smaller dito.

And, the way, the timing between the three dimmings is EXACTLY two Earth years, to the day. The telescope is orbiting the Sun every 372 days. So it looks as if it is a software problem somehow related to a calendar or a regular routine taking place on Earth.