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

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

Source: https://mysteriesdept.com/mysteries/tabbys-star/answers/ANS0DDYETY1NV0T/a-single-drop-of-about-0-1-mag-across-the-1953-1969-plate  
Publisher: Mysteries Department  
Licence: CC BY 4.0 (credit Mysteries Department and link the page)  

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[Questions](https://mysteriesdept.com/questions)[Tabby's star (KIC 8462852)](https://mysteriesdept.com/mysteries/tabbys-star)[Did the star fade over the twentieth century?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0D8E77702V2V/did-the-star-fade-over-the-twentieth-century)Answer

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 possible** Answers **1** question0

## Where it stands

**Still possible** One 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](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYFA2QEREK/both-halves-of-the-harvard-record-are-flat-and-the-offset)

Suggestive

FOR

[Sonneberg plates covering 1934-1995 show no step and no fade](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYF9R189DE/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?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0D8E77702V2V/did-the-star-fade-over-the-twentieth-century)

Part of [What causes the slow fading of the star?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0D8E76Z60339/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
```

Key

**ANS** 0DDYETY1NV0T

Kind

Answer · hypothesis

Proposed

[Session 1](https://mysteriesdept.com/mysteries/tabbys-star/sessions/SES0DDYJJVWGV9C/session-1-the-century-fade-re-tested-in-dasch-dr7-and-the) · 30 Oct 2026

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