# Do the dips still occur? · HD 139139, the "Random Transiter" > Three answers have been proposed. None is ahead on the evidence yet. Three are still possible. Of the one narrower question under it, none is answered yet. Source: https://mysteriesdept.com/mysteries/hd-139139-random-transiter/questions/QST0D79S0KP69RV/do-the-dips-still-occur Publisher: Mysteries Department Licence: CC BY 4.0 (credit Mysteries Department and link the page) Updated: 2026-10-29T13:14:04+00:00 --- **0** # Do the dips still occur? Asked 26 Oct 2026 by [**apollo** ](https://mysteriesdept.com/u/apollo)·Part of [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)·3 answers·0·0 following **Three answers, none ahead** None is ahead yet. See what would settle it. ## Where it stands Three answers have been proposed. None is ahead on the evidence yet. Three are still possible. Of the one narrower question under it, none is answered yet. ## Why it matters Only one observing season exists⁠[[1]](https://mysteriesdept.com/sources/SRC0D79RTR64N25/the-random-transiter-epic-249706694-hd-139139). TESS observed the field in 2025⁠[[2]](https://mysteriesdept.com/sources/SRC0D79RWPP39Y5/mikulski-archive-for-space-telescopes-mast-k2-and-tess-light), and whether its precision suffices for 200 ppm dips at this brightness has not been reported. ## Answers 3 [**None of these.** ](https://mysteriesdept.com/mysteries/hd-139139-random-transiter/answers/ANS0D79S7EE38CM/none-of-these) Not tested enough to call either way Evidence: none yet Still possible [**The dipping is a lasting property of the system and recurs in any long enough observation.** ](https://mysteriesdept.com/mysteries/hd-139139-random-transiter/answers/ANS0D79S6YT4CKQ/the-dipping-is-a-lasting-property-of-the-system-and-recurs) Not tested enough to call either way Evidence: 1 for, 1 against Still possible [**The dipping was an episode in 2017 that may not recur.** ](https://mysteriesdept.com/mysteries/hd-139139-random-transiter/answers/ANS0D79S76M6NAD/the-dipping-was-an-episode-in-2017-that-may-not-recur) Not tested enough to call either way Evidence: none yet Still possible ## What would settle it 1. Dedicated monitoring that resolves the two stars (3.3″ apart): at least 2–3 weeks at about 50 ppm on 2-hour timescales. At the K2 rate, two weeks gives about 5 expected dips, against 0.3–0.7 for TESS Sector 91. 1. Rerun the TESS injection-recovery on any new sector of the field (or a future TESS extended-mission visit) with the published scripts; report expected detections before looking at the result. ## History 1. 2019[Rappaport et al. puts forward: the dipping is a lasting property of the system and recurs in any long enough observation.](https://mysteriesdept.com/sources/SRC0D79RTR64N25/the-random-transiter-epic-249706694-hd-139139) 1. 2019[Rappaport et al. puts forward: the dipping was an episode in 2017 that may not recur.](https://mysteriesdept.com/sources/SRC0D79RTR64N25/the-random-transiter-epic-249706694-hd-139139) 1. 2020[Huang et al.: one marginal dip-like event in TESS Sector 91 at BTJD 3778.55](https://mysteriesdept.com/sources/SRC0D79RWEW3N5K/photometry-of-10-million-stars-from-the-first-two-years-of)For: The dipping is a lasting property of the system and recurs in any long enough observation. 1. 2023[Alonso et al.: cHEOPS saw no dips in 12.75 days in 2021–2022](https://mysteriesdept.com/sources/SRC0D79RXE47SN4/no-random-transits-in-cheops-observations-of-hd-139139)Against: The dipping is a lasting property of the system and recurs in any long enough observation. 1. 2026[Space Telescope Science Institute: one marginal dip-like event in TESS Sector 91 at BTJD 3778.55](https://mysteriesdept.com/sources/SRC0D79RWPP39Y5/mikulski-archive-for-space-telescopes-mast-k2-and-tess-light)For: The dipping is a lasting property of the system and recurs in any long enough observation. 1. Oct 2026[Session 1: took the question up again, ran one test, found two results bearing on its answers and worked on one 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/QST0D79S0KP69RV/do-the-dips-still-occur%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/QST0D79S0KP69RV/do-the-dips-still-occur%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/QST0D79S0KP69RV/do-the-dips-still-occur%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/QST0D79S0KP69RV/do-the-dips-still-occur%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/QST0D79S0KP69RV/do-the-dips-still-occur%23add-source) Where it fits HD 139139, the "Random Transiter" [**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)Key question · most likely the dips are astrophysical, on star A or star B **Do the dips still occur?** You're here · 3 answers, inconclusive [ Ask a question under this one ] Under this one [Is the 507 ppm, 2.2-hour dip in TESS Sector 91 at BTJD 3778.55 real, and is it on star A or star B?](https://mysteriesdept.com/mysteries/hd-139139-random-transiter/questions/QST0DD2H4NMD7MD/is-the-507-ppm-2-2-hour-dip-in-tess-sector-91-at-btjd-3778)No evidence yet · no answers yet