# Peter K. G. Williams 2025: DASCH: Bringing 100+ Years of Photographic Data into the 21st Century and Beyond

> Peter K. G. Williams, 2025. 5 records on Mysteries Department cite it. Describes Data Release 7 (finalised 29 December 2024), which supersedes DR1-DR6…

Source: https://mysteriesdept.com/sources/SRC0DDYCFZA4FXE/dasch-bringing-100-years-of-photographic-data-into-the-21st  
Publisher: Mysteries Department  
Licence: CC BY 4.0 (credit Mysteries Department and link the page)  

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[Sources](https://mysteriesdept.com/sources)[Tabby's star (KIC 8462852)](https://mysteriesdept.com/mysteries/tabbys-star)Peter K. G. Williams 2025

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# DASCH: Bringing 100+ Years of Photographic Data into the 21st Century and Beyond

Peter K. G. Williams, 2025.

**Tabby's star (KIC 8462852)** Article0

## What it's used for here

Describes Data Release 7 (finalised 29 December 2024), which supersedes DR1-DR6: 429,274 plate mosaics, 23.6 billion B magnitudes for 252 million sources calibrated to APASS DR8; typical light-curve rms about 0.15 mag. The release Schaefer and Hippke used in 2016 is no longer served, so DR7 is the only reproducible basis for the century-fade question. See also https://dasch.cfa.harvard.edu/dr7/ for the known-issues list, colour terms and the daschlab API.

## Cited by on this site 5 records

[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)

Evidence

EVD

[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)

Evidence

EVD

[Matched stars do not share the target's post-1969 offset](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0DDYF9DGSEKW/matched-stars-do-not-share-the-targets-post-1969-offset)

Evidence

EVD

[Matched-comparison century-slope test for DASCH light curves](https://mysteriesdept.com/methods/MTH0DDYEGKBWKWV/matched-comparison-century-slope-test-for-dasch-light-curves)

Method

MTH

[Did the star fade over the twentieth century?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0D8E77702V2V/did-the-star-fade-over-the-twentieth-century)

Question

QST

## Cite it

```
Peter K. G. Williams (2025). DASCH: Bringing 100+ Years of Photographic Data into the 21st Century and Beyond. https://arxiv.org/abs/2501.12977
```

[Find it at arxiv.org](https://arxiv.org/abs/2501.12977)

Key

**SRC** 0DDYCFZA4FXE

Kind

Journal article

Rights

The publisher's

Kept

30 Oct 2026, for editors

Added by

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

The record

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