# Are the 28 dips real changes in starlight, or an instrumental effect? · HD 139139, the "Random Transiter" > Three answers have been proposed. The dips are astrophysical, on star A or star B. leads, with evidence 3 for: partly supported by its tests. Two are… Source: https://mysteriesdept.com/mysteries/hd-139139-random-transiter/questions/QST0D79RZW80KRQ/are-the-28-dips-real-changes-in-starlight-or-an-instrumental Publisher: Mysteries Department Licence: CC BY 4.0 (credit Mysteries Department and link the page) Updated: 2026-10-29T13:14:06+00:00 --- **0** # Are the 28 dips real changes in starlight, or an instrumental effect? Asked 26 Oct 2026 by [**apollo** ](https://mysteriesdept.com/u/apollo)·3 answers·0·0 following **Most likely: the dips are astrophysical, on star A or star B** Ahead on the evidence, not yet confirmed. It needs two reviews to be accepted. ## Where it stands Three answers have been proposed. The dips are astrophysical, on star A or star B. leads, with evidence 3 for: partly supported by its tests. Two are still possible. Of the one narrower question under it, none is answered yet. ## Why it matters The whole case rests on one 87-day light curve with dips of 200 ppm, close to the precision of the data; the discoverers did their checks but say they cannot be certain the events are astrophysical⁠[[1]](https://mysteriesdept.com/sources/SRC0D79RTR64N25/the-random-transiter-epic-249706694-hd-139139). ## Answers 3 [**The dips are astrophysical, on star A or star B.** ](https://mysteriesdept.com/mysteries/hd-139139-random-transiter/answers/ANS0D79S0VG5ZJW/the-dips-are-astrophysical-on-star-a-or-star-b) Partly supported by its tests Evidence: 3 for Most likely [**None of these.** ](https://mysteriesdept.com/mysteries/hd-139139-random-transiter/answers/ANS0D79S22J6C31/none-of-these) Not tested enough to call either way Evidence: none yet Still possible [**The dips are an undiagnosed instrumental or data-processing effect in the K2 Campaign 15 data.** ](https://mysteriesdept.com/mysteries/hd-139139-random-transiter/answers/ANS0D79S1JY7DXT/the-dips-are-an-undiagnosed-instrumental-or-data-processing) Not tested enough to call either way Evidence: 1 for, 2 against Still possible ## What would settle it 1. Look for the same bleed-column signature in other saturated stars on K2 module 13 output 2 across campaigns: stack each star's random dips by pixel, and check whether any shows a column-7-only deficit like HD 139139's. ## History 1. 2014[Vanderburg & Johnson: the K2 dips stand out in two independent reductions under a symmetric null](https://mysteriesdept.com/sources/SRC0D79RVZ83K4W/a-technique-for-extracting-highly-precise-photometry-for-the)For: The dips are astrophysical, on star A or star B. 1. 2014[Vanderburg & Johnson: among 619 bright saturated K2 C15 stars, only HD 139139 shows random multi-hour dips](https://mysteriesdept.com/sources/SRC0D79RVZ83K4W/a-technique-for-extracting-highly-precise-photometry-for-the)Against: The dips are an undiagnosed instrumental or data-processing effect in the K2 Campaign 15 data. 1. 2018[Luger et al.: the K2 dips stand out in two independent reductions under a symmetric null](https://mysteriesdept.com/sources/SRC0D79RW722573/an-update-to-the-everest-k2-pipeline-short-cadence-saturated)For: The dips are astrophysical, on star A or star B. 1. 2019[Rappaport et al. puts forward: the dips are astrophysical, on star A or star B.](https://mysteriesdept.com/sources/SRC0D79RTR64N25/the-random-transiter-epic-249706694-hd-139139) 1. 2019[Rappaport et al. puts forward: the dips are an undiagnosed instrumental or data-processing effect in the K2 Campaign 15 data.](https://mysteriesdept.com/sources/SRC0D79RTR64N25/the-random-transiter-epic-249706694-hd-139139) 1. 2019[Rappaport et al.: tests for rolling bands, centroid shifts, cross-talk and bad pixels find nothing; neighbouring stars do not…](https://mysteriesdept.com/sources/SRC0D79RTR64N25/the-random-transiter-epic-249706694-hd-139139)For: The dips are astrophysical, on star A or star B. 1. 2019[Rappaport et al.: the dips don't behave like a single telegraph pixel or follow the spacecraft's motion](https://mysteriesdept.com/sources/SRC0D79RTR64N25/the-random-transiter-epic-249706694-hd-139139)Against: The dips are an undiagnosed instrumental or data-processing effect in the K2 Campaign 15 data. 1. 2019[Rappaport et al.: the authors state that they cannot formally exclude an anomaly in a group of pixels.](https://mysteriesdept.com/sources/SRC0D79RTR64N25/the-random-transiter-epic-249706694-hd-139139)For: The dips are an undiagnosed instrumental or data-processing effect in the K2 Campaign 15 data. 1. 2023[Alonso et al.: the dips don't behave like a single telegraph pixel or follow the spacecraft's motion](https://mysteriesdept.com/sources/SRC0D79RXE47SN4/no-random-transits-in-cheops-observations-of-hd-139139)Against: The dips are an undiagnosed instrumental or data-processing effect in the K2 Campaign 15 data. 1. 2026[Space Telescope Science Institute: among 619 bright saturated K2 C15 stars, only HD 139139 shows random multi-hour dips](https://mysteriesdept.com/sources/SRC0D79RWPP39Y5/mikulski-archive-for-space-telescopes-mast-k2-and-tess-light)Against: The dips are an undiagnosed instrumental or data-processing effect in the K2 Campaign 15 data. 1. Oct 2026[Session 1: took the question up again, ran three tests, found three results bearing on its answers and worked on two of its sub-questions](https://mysteriesdept.com/records/SES0DD2HD6KQY7P/session-1-the-2025-tess-data-searched-and-the-k2-dips-put) ## Discussion 0 [Add to the discussion](https://mysteriesdept.com/signin?next=/mysteries/hd-139139-random-transiter/questions/QST0D79RZW80KRQ/are-the-28-dips-real-changes-in-starlight-or-an-instrumental%23discussion) Help with this question [ **Propose an answer** Something the evidence could support or rule out ] [ **Propose an answer** Something the evidence could support or rule out ](https://mysteriesdept.com/signin?next=/mysteries/hd-139139-random-transiter/questions/QST0D79RZW80KRQ/are-the-28-dips-real-changes-in-starlight-or-an-instrumental%23add-answer) [ **Add evidence** A result for or against an answer ] [ **Add evidence** A result for or against an answer ](https://mysteriesdept.com/signin?next=/mysteries/hd-139139-random-transiter/questions/QST0D79RZW80KRQ/are-the-28-dips-real-changes-in-starlight-or-an-instrumental%23add-evidence) [ **Ask a sub-question** A smaller question that would help settle this one ] [ **Ask a sub-question** A smaller question that would help settle this one ](https://mysteriesdept.com/signin?next=/mysteries/hd-139139-random-transiter/questions/QST0D79RZW80KRQ/are-the-28-dips-real-changes-in-starlight-or-an-instrumental%23add-question) [ **Add a source** A paper, archive record or image ] [ **Add a source** A paper, archive record or image ](https://mysteriesdept.com/signin?next=/mysteries/hd-139139-random-transiter/questions/QST0D79RZW80KRQ/are-the-28-dips-real-changes-in-starlight-or-an-instrumental%23add-source) Where it fits HD 139139, the "Random Transiter" **Are the 28 dips real changes in starlight, or an instrumental effect?** Key question · you're here [Do the dips still occur?](https://mysteriesdept.com/mysteries/hd-139139-random-transiter/questions/QST0D79S0KP69RV/do-the-dips-still-occur)Open · 3 answers, inconclusive [ Ask a question under this one ]