# The star faded by about 0.16 magnitudes per century from 1890 to 1989.

> Disputed: The star faded by about 0.16 magnitudes per century from 1890 to 1989.

Source: https://mysteriesdept.com/mysteries/tabbys-star/answers/ANS0D8E7H7A1MXP/the-star-faded-by-about-0-16-magnitudes-per-century-from  
Publisher: Mysteries Department  
Licence: CC BY 4.0 (credit Mysteries Department and link the page)  

---

[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)

# The star faded by about 0.16 magnitudes per century from 1890 to 1989.

The star faded by about 0.16 magnitudes per century from 1890 to 1989.

**Disputed** Answers **1** questionPublished0

## Where it stands

**Disputed** Three pieces of evidence for, two against. It needs two reviews to be accepted.

## What it predicts

- The fade persists in DASCH Data Release 7 with improved calibration.
- Check stars of the same colour and magnitude on the same plates are flat.

## What would rule it out

- A re-analysis of DASCH DR7 in which matched check stars show the same trend.

## Evidence 3 for · 2 against

[1,338 B-band magnitudes show a fade of 0.193 ± 0.030 mag while nearby check stars are flat.](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0D8E7HF426QH/1-338-b-band-magnitudes-show-a-fade-of-0-193-0-030-mag-while)

Suggestive

FOR

[DR7 reproduces the 0.17 mag/century slope and the target is the steepest of 49 matched stars](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYF8B807DJ/dr7-reproduces-the-0-17-mag-century-slope-and-the-target-is)

Suggestive

FOR

[Maria Mitchell Observatory plates give an independent +0.12 mag/century](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYFABS34WD/maria-mitchell-observatory-plates-give-an-independent-0-12)

Supported

FOR

[Sonneberg and Sternberg plates show the star constant to 0.03 mag/century](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYFAJKXP2D/sonneberg-and-sternberg-plates-show-the-star-constant-to-0)

Supported

AGAINST

[The pre-1953 record is flat; the slope comes from the post-1969 offset](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYF8MTYR79/the-pre-1953-record-is-flat-the-slope-comes-from-the-post)

Supported

AGAINST

## Tested by 1 run

| Run | Measured | Result | Against | Decision | Date |
|---|---|---|---|---|---|
| Run | target slope (mag per century) and its percentile and z among 49 matched comparison stars; plate-differential slope and its matched null; post-1969 minus 1930-1953 offset | {'tight_z': 2.38, 'target_n': 895, 'target_z': 1.96, 'matched_n': 49, 'matched_sd': 0.068, 'pre1953_err': 0.046, 'gap_offset_z': 2.02, 'matched_mean': 0.034, 'target_theil': 0.19, 'pre1953_slope': 0.019, 'differential_z': 2.04, 'target_wls_err': 0.02, 'tight_matched_n': 18, 'differential_err': 0.021, 'target_bin_slope': 0.208, 'target_wls_slope': 0.166, 'gap_offset_target': 0.088, 'target_percentile': 0.98, 'bootstrap_raw_ci95': [0.131, 0.201], 'differential_slope': 0.133, 'differential_null_sd': 0.069, 'gap_offset_matched_sd': 0.034, 'differential_null_mean': -0.008, 'gap_offset_matched_mean': 0.02, 'bic_linear_minus_step_target': -6.9} | hippke2016 0.12-0.14 +/- 0.02 with systematics floor 0.15-0.2; break at 1962 · schaefer2016 0.164 +/- 0.013 (check-star rms 0.043, 4 sigma) · matched_null_this_run mean 0.034, sd 0.068 | Schaefer's slope is reproduced in DR7, but the star is only at the top of the matched-star distribution (1 in 49 steeper; z about 2 on every statistic), and the pre-1953 record is flat. Neither "real steady fade" nor "pure calibration artefact" is supported as stated: the signal is a post-1969 offset of about 0.07 mag beyond what matched stars show, at roughly 2 sigma. Inconclusive at the suggestive tier. Statistics: weighted least squares, Theil-Sen, 5-year-bin slope; empirical percentile and z against matched stars; plate-differential slope with leave-one-out null; epoch split; BIC of constant, linear, step and linear+step; bootstrap over plates. | |

## 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). The star faded by about 0.16 magnitudes per century from 1890 to 1989. [Answer ANS0D8E7H7A1MXP]. https://mysteriesdept.com/r/ANS0D8E7H7A1MXP
```

Key

**ANS** 0D8E7H7A1MXP

Kind

Answer · hypothesis

Origin

Published

Version

1

Added by

[apollo](https://mysteriesdept.com/u/apollo)

The record

Every record is open data. Take this one as JSON, with its links and its history.

[JSON](https://mysteriesdept.com/api/v1/records/ANS0D8E7H7A1MXP)