Answer · Tabby's star (KIC 8462852)

The 2019 dip is the transit of a giant planet on an orbit of roughly 1,030 to 1,370 days.

Still possibleAnswers 1 question0

Where it stands

Still possibleOne piece of evidence for, one against. It needs two reviews to be accepted.

What it predicts

A transit of about 1.1 per cent and 21 hours at a date in one of the allowed windows (next: late February 2027 for the 1,345-1,368 day windows; mid-February 2028 for the 1,030 day window).
No transit of that depth at any other time.
The transit shape is symmetric and limb-darkened, unlike the structured Kepler dips.
The radial-velocity signal grows past 3 sigma with more SOPHIE epochs.

What would rule it out

Continuous photometry through every allowed window with no transit.
Radial velocities that exclude a companion above about 1 Jupiter mass at those periods.

Evidence 1 for · 1 against

The 2019 dip has the shape of a limb-darkened transit, not a dust cloud

Supported

FOR

AAVSO observers covered the 18-23 October 2026 window and saw no transit over most of it

Suggestive

AGAINST

Kepler and TESS coverage alone exclude 80 per cent of periods and reproduce the published windows

Established

NEUTRAL

Tested by 1 run

Run	Measured	Result	Against	Decision	Date
Run	fraction of periods excluded; allowed ranges; per-window past/next transit dates and coverage; recurrence-window coverage fractions	{'next_transits': {'W1': ['2022-06-29..07-01 (8 d before S54)', '2025-04-24..27', '2028-02-17..23'], 'W3': ['2023-03-27..30', '2026-10-18..23', '2030-05-11..19'], 'W4': ['2023-05-11', '2027-01-15..16'], 'W5': ['2023-06-01..02', '2027-02-28..03-02']}, 'W1_survives_because': '2011-03-15..20 falls in the Q8/Q9 gap', 'coverage_days_total': 1522.6, 'excluded_as_printed': {'W2': 'Kepler 2011-03-03..06', 'W4': 'Kepler 2012-04-21'}, 'allowed_near_published': {'W1': [1029.45, 1031.7], 'W3': [1300.2, 1304.05], 'W5': [1365.85, 1368.5], 'nearest_to_W4': [1354.4, 1356.1]}, 'fraction_excluded_100_3000d': 0.804, 'recurrence_coverage_fraction': {'n1_2013': 0.56, 'n4_2019': 0.07, 'n5_2021': 0.09, 'n6_2024': 0.05}}		Coverage alone reproduces the published windows 1, 3 and 5 and shows windows 2 and 4 as printed are excluded (typographical). The most recent predicted return, window 3 on 18-23 October 2026, had no space coverage; the next falls in January to March 2027 near solar conjunction, then 17-23 February 2028. The recurrence model is essentially untested by TESS.

The questions it answers

Is the 1.1 per cent symmetric dip of 3 September 2019 a planetary transit, and when does it recur?

Part of What blocks the light during the deep, irregular dips?

Open2 answers, none ahead

Cite it

Mysteries Department. (2026). The 2019 dip is the transit of a giant planet on an orbit of roughly 1,030 to 1,370 days. [Answer ANS0DEC112MA2C4]. https://mysteriesdept.com/r/ANS0DEC112MA2C4

@misc{mysteriesdept_ans0dec112ma2c4,
  title     = {The 2019 dip is the transit of a giant planet on an orbit of roughly 1,030 to 1,370 days.},
  author    = {{Mysteries Department}},
  year      = {2026},
  note      = {Answer, catalog key ANS0DEC112MA2C4},
  url       = {https://mysteriesdept.com/r/ANS0DEC112MA2C4}
}