Tabby's star (KIC 8462852)Evidence
Evidence · Tabby's star (KIC 8462852)
Kepler and TESS coverage alone exclude 80 per cent of periods and reproduce the published windows
Assuming strict periodicity from the 2019 mid-time, 80 per cent of periods between 100 and 3,000 days would have put a transit inside Kepler or TESS coverage; the surviving ranges include 1,029.5-1,031.7, 1,300.2-1,304.1 and 1,365.9-1,368.5 days, matching the published windows 1, 3 and 5, while windows 2 (1,034.5-1,035.3) and 4 (1,345.6) as printed are excluded by Kepler transits on 3-6 March 2011 and 21 April 2012 and are evidently typographical (the paper's own Table 3 puts window 2 at 1,031.5
What it means
Key questionWhat blocks the light during the deep, irregular dips?
Most likely: clumps of fine dust orbiting the star, released by comets, planetesimals or other bodies close to it
Most likelyunchanged
Part of itIs the 1.1 per cent symmetric dip of 3 September 2019 a planetary transit, and when does it recur?
2 answers, none ahead yet
Openunchanged
Answer this evidence bears onThe 2019 dip is the transit of a giant planet on an orbit of roughly 1,030 to 1,370 days.
Bears on1 for, 1 against
Still possibleunchanged
Next steps 4
1
Extract a Sector 75 light curve from the FFIs with TESScut and run the same dip search; it is the one covered sector with no light-curve product.
~3 h
—not judged
2
Fit the 2019 transit with a free eccentric orbit and a ring (Zhu et al. 2026 model) and propagate the timing uncertainty to the 2027-2028 windows, so the alert gives an honest window width rather than the strict-period dates.
~6 h
—not judged
3
Close the 1,301.44-1,301.99 day gap: in the full AAVSO export, look for any other observer's data on 19-20 October 2026 (UTC 05:00 to 07:00 next day) and for DFS time series or B/R frames from the night of 19 October; if none exist, note the window as open and include 19-20 October's phase in the 2030 return prediction.
~1 h
—not judged
4
Post an observing request (AAVSO alert notice or forum) for the next predicted returns: 15-16 January 2027 (if window 4 is 1,355-1,356 d as the coverage map suggests), 28 February to 2 March 2027 (window 5), and 17-23 February 2028 (window 1), with the expected depth of 1.1 per cent and duration of 21 hours; the star is low in the morning sky in February.
~1 h
—not judged
Ranked by how likely each is to move the key question, for the time it takes
How it was found 1 run
Result. 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..
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.
Kepler long-cadence light curve of KIC 8462852, Quarters 0-17, as one CSVTESS light curves of TIC 185336364 (KIC 8462852), Sectors 14-82, as flat CSVcode/transit_windows.py3 outputs
Notes from the run
Kepler and TESS coverage intervals are read from the data files; 2015-2018 ground photometry is not used for exclusion. Future TESS sectors (expected 2027) are not in the coverage table.
Sources 1
Evidence for a giant companion orbiting Tabby's star
SRCMadurga-Favieres 2026
Cite it
Mysteries Department. (2026). Kepler and TESS coverage alone exclude 80 per cent of periods and reproduce the published windows [Evidence EVD0DEC1DH5506X]. https://mysteriesdept.com/r/EVD0DEC1DH5506X
@misc{mysteriesdept_evd0dec1dh5506x,
title = {Kepler and TESS coverage alone exclude 80 per cent of periods and reproduce the published windows},
author = {{Mysteries Department}},
year = {2026},
note = {Evidence, catalog key EVD0DEC1DH5506X},
url = {https://mysteriesdept.com/r/EVD0DEC1DH5506X}
}