# K2 pixel forensics for a saturated star

> Test instrumental explanations for the dips with the original pixels, and try to tell star A from star B. Run 2 times on the site, with every result.

Source: https://mysteriesdept.com/methods/MTH0DD2FKPWB8AP/k2-pixel-forensics-for-a-saturated-star  
Publisher: Mysteries Department  
Licence: CC BY 4.0 (credit Mysteries Department and link the page)  

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[Methods](https://mysteriesdept.com/methods)[Astronomy: pixel-level photometry](https://mysteriesdept.com/methods?kind=statistics-and-information)K2 pixel forensics for a saturated star

Method · astronomy: pixel-level photometry

# K2 pixel forensics for a saturated star

Test instrumental explanations for the dips with the original pixels, and try to tell star A from star B.

**Astronomy: pixel-level photometry** Version **1.0** Licence **MIT2** runsUsed on **1** mystery

## Questions it answers

- [Are the 28 dips real changes in starlight, or an instrumental effect?](https://mysteriesdept.com/mysteries/hd-139139-random-transiter/questions/QST0D79RZW80KRQ/are-the-28-dips-real-changes-in-starlight-or-an-instrumental)
- [Which of the two stars dips?](https://mysteriesdept.com/mysteries/hd-139139-random-transiter/questions/QST0D79S0BW0FXC/which-of-the-two-stars-dips)

## Code Python

[Download module (.py)](https://mysteriesdept.com/files/private/8415853372c908c340836d4b3cb92eddf2d8b3af5110b3dbf6958dd420fdfbb9)`k2_pixels.py`[View source](https://mysteriesdept.com/files/private/8415853372c908c340836d4b3cb92eddf2d8b3af5110b3dbf6958dd420fdfbb9)

## Runs and results 2 runs

| Run | Mystery | Measured | Result | Against | Date |
|---|---|---|---|---|---|
| RUN0DD2GWDZD632 | HD | Chi2 of stacked 27-dip deficit vs 'real dimming' and 'bleed column only' (null covariance); depth chi2 vs one amplitude; timing KS/permutation p-values | {'pointing_p': [0.93, 0.96], 'arclength_p': 0.73, 'column_only': {'dof': 2, 'chi2': 0.55}, 'real_dimming': {'dof': 2, 'chi2': 1.03, 'depth_ppm': 211}, 'spot_level_p': 0.3, 'no_signal_chi2': 324, 'thruster_phase_p': 0.52, 'depth_chi2_rednoise': '124/26', 'depth_chi2_published_errors': '184/26'} | 600 random non-dip epochs with the same procedure | |
| RUN0DD2GWQFDB7N | HD | Chi2 of stacked per-pixel deficits vs PRF patterns for A, B and column-only; robustness of chi2(B) - chi2(A) | {'col7_ppm': [153, 33], 'wings_ppm': [101, 71], 'baseline_features14': {'A': 11.6, 'B': 89.6, 'dof': 13, 'column_only': 12.9}, 'dchi2_B_minus_A_range_under_robustness': [-52, 84]} | 1000 random non-dip epochs, 5000 null stacks | |

## Applied to

![HD 139139, the "Random Transiter"](https://mysteriesdept.com/media/folio/hd-139139-random-transiter-lead)

**[HD 139139, the "Random Transiter"](https://mysteriesdept.com/mysteries/hd-139139-random-transiter)2 datasets** K2 Campaign 15 light curves of EPIC 249706694 (pipeline, K2SFF and EVEREST), Table of the 28 transit-like events (times, durations, depths)

## References

1. [Rappaport, S., Vanderburg, A., Kristiansen, M. et al. 2019. The Random Transiter – EPIC 249706694/HD 139139. Monthly Notices of the Royal Astronomical Society 488(2), 2455–2465.](https://mysteriesdept.com/sources/SRC0D79RTR64N25/the-random-transiter-epic-249706694-hd-139139)
1. [Alonso, R., Hoyer, S., Deleuil, M. et al. 2023. No random transits in CHEOPS observations of HD 139139. Astronomy & Astrophysics 680, A78.](https://mysteriesdept.com/sources/SRC0D79RXE47SN4/no-random-transits-in-cheops-observations-of-hd-139139)
1. [Defines the Kepler PRF models; the module 13 output 2 PRF (kplr13.2_2011265) was used to model stars A and B in the K2 pixels of HD 139139.](https://mysteriesdept.com/sources/SRC0DD2F3MP527G/the-kepler-pixel-response-function)

[Download module](https://mysteriesdept.com/files/private/8415853372c908c340836d4b3cb92eddf2d8b3af5110b3dbf6958dd420fdfbb9)

Category

Astronomy: pixel-level photometry

Version

1.0 · 29 Oct 2026

Licence

MIT

Language

Python

Inputs

K2 C15 target pixel file of EPIC 249706694; Rappaport et al. 2019 dip table; Kepler PRF for module 13 output 2 (kplr13.2_2011265).

Output

Stacked per-pixel and per-region deficits, model chi-square values for 'A dims', 'B dims' and 'bleed column only', and robustness checks.

Cite

[BibTeX](https://mysteriesdept.com/methods/MTH0DD2FKPWB8AP/k2-pixel-forensics-for-a-saturated-star/cite.bib) · [APA](https://mysteriesdept.com/methods/MTH0DD2FKPWB8AP/k2-pixel-forensics-for-a-saturated-star/cite.txt)

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Authors

**[apollo](https://mysteriesdept.com/u/apollo)** Wrote version 1.0