What the corrected fit shows

Transit supportSUPPORTED (ΔBIC ≥ 10)

Fitted midpoint shift+0.016 h

Model depth11644.2 ± 73.1 ppm

ΔBIC (null − transit)60210.1

The timing-adjusted transit is strongly preferred by ΔBIC = 60210.1. Its fitted midpoint is +0.016 hours from the historical prediction; the model's mid-transit depth is 11644.2 ± 73.1 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-127 b — The dotted vertical line is the historical archive prediction; the dashed colored line marks the fitted midpoint (+0.016 h). The smooth curve fits timing, radius ratio, impact parameter, and a local linear baseline.

Explicit model comparison

Linear nullχ² 67332.58 / 3207 dof

BIC = 67348.73

Limb-darkened transitχ² 7098.23 / 3204 dof

BIC = 7138.60

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 depth11644.2 +/- 215.5 ppm

Supported / fitted sectors1 / 1

Residual beta range2.95-2.95

The archive prediction was timing-adjusted independently in 1 fitted sector(s) (S9), 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 2.95-2.95). The robust inverse-variance model depth across supported sectors is 11644.2 +/- 215.5 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-127 b — Independent sector transit fits. Reproduced from the committed public TESS SPOC files.

Sector depth consistency for WASP-127 b — Sector depth consistency. Reproduced from the committed public TESS SPOC files.

Residual RMS time-averaging diagnostic for WASP-127 b — Residual RMS time-averaging diagnostic. Reproduced from the committed public TESS SPOC files.

The system

Radius	14.69 Earth radii
Mass	52.35 Earth masses
Orbital period	4.178062 days
Transit duration	4.353 hours
Semi-major axis	0.0484 AU
Equilibrium temperature	1400 K
Host and distance	WASP-127 · 159.51 pc
Discovery	2016 · 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 tess2019058134432-s0009-0000000169226822-0139-s_lc.fits, TESS Sector 9, 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

Lam et al. 2017 — 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 9 used here.
NASA Exoplanet Archive, saved TAP row retrieved 2026-08-15.