Answer · Tabby's star (KIC 8462852)

A single drop of about 0.1 mag across the 1953-1969 plate gap, not a steady century fade

The star dropped by about 0.1 magnitude once, between the 1950s and the 1970s, and was otherwise constant on the plates.

Still possibleAnswers 1 question0

Where it stands

Still possibleOne piece of evidence for, one against. It needs two reviews to be accepted.

What it predicts

Matched comparison stars on the same Harvard plates do not share the post-1969 offset.
Independent archives with continuous coverage across 1950-1975 (Sonneberg, Maria Mitchell) show a step of similar size at the same time.
Within 1890-1953 and within 1969-1990 the star is constant.

What would rule it out

A per-plate differential analysis in which matched stars show the same post-1969 offset as the target.
Independent archives flat across 1950-1975 to better than 0.05 mag with the target's colour and magnitude controlled.

Evidence 1 for · 1 against

Both halves of the Harvard record are flat and the offset between them is not shared by matched stars

Suggestive

FOR

Sonneberg plates covering 1934-1995 show no step and no fade

Supported

AGAINST

The questions it answers

Did the star fade over the twentieth century?

Part of What causes the slow fading of the star?

Open4 answers, none ahead

Cite it

Mysteries Department. (2026). A single drop of about 0.1 mag across the 1953-1969 plate gap, not a steady century fade [Answer ANS0DDYETY1NV0T]. https://mysteriesdept.com/r/ANS0DDYETY1NV0T

@misc{mysteriesdept_ans0ddyety1nv0t,
  title     = {A single drop of about 0.1 mag across the 1953-1969 plate gap, not a steady century fade},
  author    = {{Mysteries Department}},
  year      = {2026},
  note      = {Answer, catalog key ANS0DDYETY1NV0T},
  url       = {https://mysteriesdept.com/r/ANS0DDYETY1NV0T}
}