What the corrected fit shows

Transit supportSUPPORTED (ΔBIC ≥ 10)

Fitted midpoint shift-0.002 h

Model depth17223.7 ± 80.6 ppm

ΔBIC (null − transit)134924.8

The timing-adjusted transit is strongly preferred by ΔBIC = 134924.8. Its fitted midpoint is -0.002 hours from the historical prediction; the model's mid-transit depth is 17223.7 ± 80.6 ppm. The support decision uses ΔBIC ≥ 10; timing-search p-values are not presented as blind-detection probabilities.

Timing-adjusted limb-darkened transit fit for WASP-69 b — The dotted vertical line is the historical archive prediction; the dashed colored line marks the fitted midpoint (-0.002 h). The smooth curve fits timing, radius ratio, impact parameter, and a local linear baseline.

Explicit model comparison

Linear nullχ² 138888.35 / 1571 dof

BIC = 138903.07

Limb-darkened transitχ² 3941.46 / 1568 dof

BIC = 3978.26

The null fits a local intercept and slope. The transit adds bounded midpoint, radius-ratio, and impact-parameter freedom while retaining the same baseline terms. Fixed limb darkening and circular geometry make this a diagnostic fit rather than a full system retrieval.

Multi-sector robustness and noise

Supported combined depth17223.7 +/- 330.9 ppm

Supported / fitted sectors1 / 1

Residual beta range4.11-4.11

The archive prediction was timing-adjusted independently in 1 fitted sector(s) (S55), of which 1 meet Delta BIC >= 10. Formal depth errors were inflated by sqrt(max(reduced chi-square, 1)) times the residual time-averaging beta factor (observed range 4.11-4.11). The robust inverse-variance model depth across supported sectors is 17223.7 +/- 330.9 ppm; a sector-to-sector Q test requires at least two supported sectors. These scaled errors address underestimated scatter and short-timescale correlation, but they are not a full Gaussian-process or physical limb-darkened transit fit.

Independent sector transit fits for WASP-69 b — Independent sector transit fits. Reproduced from the committed public TESS SPOC files.

Sector depth consistency for WASP-69 b — Sector depth consistency. Reproduced from the committed public TESS SPOC files.

Residual RMS time-averaging diagnostic for WASP-69 b — Residual RMS time-averaging diagnostic. Reproduced from the committed public TESS SPOC files.

The system

Radius	11.21 Earth radii
Mass	82.58 Earth masses
Orbital period	3.868139 days
Transit duration	2.187 hours
Semi-major axis	0.0453 AU
Equilibrium temperature	971 K
Host and distance	WASP-69 · 49.96 pc
Discovery	2014 · Transit · SuperWASP

Values are from the exact saved NASA Exoplanet Archive pscomppars row in data/system_parameters.csv.

Data and reproducibility

The observed photometry is the public MAST file tess2022217014003-s0055-0000000248853232-0242-s_lc.fits, TESS Sector 55, collection DOI 10.17909/t9-nmc8-f686. It is stored unmodified. Exact archive URI, URL, retrieval date, and checksum are in data/SOURCE.md.

Run python scripts/analyze_transit.py and python scripts/analyze_multisector.py to regenerate the figures and CSVs, then pytest tests/ -v to check the documented values against the real file.

Limitations

The orbit is circular and the quadratic limb-darkening coefficients are fixed representative values.
The scaled semi-major axis comes from saved composite values whose uncertainties are not propagated.
The midpoint is searched within a bounded window; ΔBIC is used as the support gate.
PDCSAP processing, dilution, stellar variability, timing variations, and covariance can bias the geometry.
Published global fits with physical priors, instrument-specific detrending, and simultaneous sectors remain authoritative.

References

Anderson et al. 2014 — discovery reference listed by the NASA Exoplanet Archive.
Ricker et al. (2015), Transiting Exoplanet Survey Satellite (TESS), doi:10.1117/1.JATIS.1.1.014003.
TESS Team, TESS Light Curves — All Sectors, MAST, doi:10.17909/t9-nmc8-f686; Sector 55 used here.
NASA Exoplanet Archive, saved TAP row retrieved 2026-08-15.