Run · Tabby's star (KIC 8462852)

Shape of the 2019 dip: transit, trapezoid and dust-profile fits, and asymmetry against the Kepler dips

D260 and D426 are dropped from the asymmetry table (too shallow for stable half-depth crossings). The 2019 model-free asymmetry is noisy; the model comparison is the primary result.

The limb-darkened transit is the preferred shape by a wide margin and its duration is consistent with a thousand-day circular orbit around this star; the deep Kepler dips are uniformly skewed in the opposite sense. Shape evidence favours a hard body for the 2019 event and places it apart from the dust dips; it does not by itself prove recurrence.{'dBIC': {'planet': 0, 'gaussian': 195.8, 'skewgauss': 201, 'trapezoid': 26.8}, 'planet': {'b': 0.79, 'a_rs': 296, 'rp_rs': 0.11, 't0_BTJD': 1730.156, 'depth_pct': 1.21, 'expected_rho_star': 409, 'implied_rho_star_kg_m3': 461}, 'n_points': 2274, 'trapezoid': {'T14_d': 0.856, 'egress_d': 0.29, 'depth_pct': 1.17, 'ingress_d': 0.186}, 'planet_chi2': 2365, 'skewgauss_asymmetry': 0.89, 'asymmetry_2019_binned': {'A': 1.29, 'depth_pct': 1.25, 'deficit_before': 0.59}, 'asymmetry_kepler_deep': {'D140': [0.75, 0.44], 'D792': [0.77, 0.42], 'D1495': [0.6, 0.38], 'D1519': [0.65, 0.36], 'D1540': [0.57, 0.36], 'D1568': [0.6, 0.35]}}0

Result

Run	Measured	Result	Against	Decision	Date
Run	BIC per model; derived transit parameters; ingress/egress ratio and deficit fraction before minimum per dip	{'dBIC': {'planet': 0, 'gaussian': 195.8, 'skewgauss': 201, 'trapezoid': 26.8}, 'planet': {'b': 0.79, 'a_rs': 296, 'rp_rs': 0.11, 't0_BTJD': 1730.156, 'depth_pct': 1.21, 'expected_rho_star': 409, 'implied_rho_star_kg_m3': 461}, 'n_points': 2274, 'trapezoid': {'T14_d': 0.856, 'egress_d': 0.29, 'depth_pct': 1.17, 'ingress_d': 0.186}, 'planet_chi2': 2365, 'skewgauss_asymmetry': 0.89, 'asymmetry_2019_binned': {'A': 1.29, 'depth_pct': 1.25, 'deficit_before': 0.59}, 'asymmetry_kepler_deep': {'D140': [0.75, 0.44], 'D792': [0.77, 0.42], 'D1495': [0.6, 0.38], 'D1519': [0.65, 0.36], 'D1540': [0.57, 0.36], 'D1568': [0.6, 0.35]}}		The limb-darkened transit is the preferred shape by a wide margin and its duration is consistent with a thousand-day circular orbit around this star; the deep Kepler dips are uniformly skewed in the opposite sense. Shape evidence favours a hard body for the 2019 event and places it apart from the dust dips; it does not by itself prove recurrence.

What it used and found

Dip-shape model comparison and asymmetry statistic

Method

MTH

Kepler long-cadence light curve of KIC 8462852, Quarters 0-17, as one CSV

Dataset

DAT

TESS light curves of TIC 185336364 (KIC 8462852), Sectors 14-82, as flat CSV

Dataset

DAT

The 2019 dip is a single compact dust clump of the same family as the Kepler and 2017 dips, and will not recur on a…

Answer it tests

ANS

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

Evidence it produced

EVD

The deep Kepler dips are all skewed; the 2019 dip is not

Evidence it produced

EVD

Parameters

seed = 7, starts = 12, window_d = 1.6, limb_darkening = [0.32, 0.22], period_fixed_d = 1031, kepler_dips_BKJD = [140.5, 260.9, 359.1, 426.6, 502.3, 792.7, 1205.9, 1495.9, 1519.6, 1540.4, 1568.5], asymmetry_cadence_min = 29.4

Cite it

Mysteries Department. (2026). Shape of the 2019 dip: transit, trapezoid and dust-profile fits, and asymmetry against the Kepler dips [Run RUN0DEC25RSHDJ9]. https://mysteriesdept.com/r/RUN0DEC25RSHDJ9

@misc{mysteriesdept_run0dec25rshdj9,
  title     = {Shape of the 2019 dip: transit, trapezoid and dust-profile fits, and asymmetry against the Kepler dips},
  author    = {{Mysteries Department}},
  year      = {2026},
  note      = {Run, catalog key RUN0DEC25RSHDJ9},
  url       = {https://mysteriesdept.com/r/RUN0DEC25RSHDJ9}
}