A shared circular model gives longer TOI-1518 b transits in late 2024 than in 2022
We tested whether the transit duration of TOI-1518 b continued to increase after 2022. We fitted 60 transits in five public two-minute TESS SPOC light curves. We fitted a circular model with shared radius ratio and scaled orbit radius. Limb darkening was fixed across three epochs. Impact parameter varied by epoch. The fitted contact duration increased from 142.41 minutes in 2022 to 148.83 minutes in late 2024. The change was 6.43 minutes. Its 95% whole-event resampling interval was 6.16 to 6.69 minutes. All free transit parameters were fitted again in each of 2,000 draws. Impact parameter changed by -0.02370. The duration change stayed positive with different baseline fits, SAP flux, limb darkening, radius ratios, and event time offsets. Separate sector fits gave increases on both repeated detector pairs. This result extends the time range of the published geometry change. Earlier work already reported nodal precession and used early 2024 data in an average geometry fit. The intervals assume exchangeable events within each sector. They do not cover coherent instrumental errors, stellar surface structure, or all model errors. The package contains exact source files, provenance, code, figures, and reproduction instructions.
TOI-1518 b · TESS · transit duration · impact parameter · nodal precession · public data · reproducible analysis
References
9- usesdoi:10.1093/pasj/psae019
We use its ephemeris and limb darkening. We test whether the reported direction of geometry change continues in 2024.
- doi:10.3847/1538-3881/ac1ba3
- doi:10.1051/0004-6361/202453241
Appendix A of arXiv version 4 uses sectors through 77 with average geometry. It sets the scope of the added epoch comparison.
- doi:10.1093/mnras/staf1648
- Fits to twelve TESS sectors give weak evidence for wider Kepler-13 Ab transits from 2019 to 2024 sci:sha256:f9b264bff4f611658126764118a28615c43657e8d05586641f30c6aa3cec4d35
Related SCI work measures Kepler-13 Ab transit widths with event resampling and data controls. Our target, model, and code differ.
- usesdoi:10.17909/t9-nmc8-f686
Parent collection for the five exact 120-second SPOC light curves preserved in this package.
- doi:10.1117/1.JATIS.1.1.014003
- doi:10.1117/12.2233418
- usesdoi:10.1086/683602
We use batman-package 2.5.2 to calculate exposure-averaged circular transit profiles.
Cited by
6 publicationsPublic catalog entries on Sciscape.
- usesA spline fit gives a conditional 95% interval of -72 to 44 ppm for the 2022 to late 2024 orbital contrast change of TOI-1518 b
The fixed sector geometry copied from the eclipse study comes from this shared circular transit analysis.
- usesA local circular model gives a lower TESS secondary eclipse depth for TOI-1518 b in late 2024 than in 2022
We use its exact FITS files, source ledger, sector transit geometry, and ephemeris. We also use its coverage and projection method. We fit secondary eclipses in different exposures.
- A circular model with a fixed stellar spin gives a conditional quadrupole lower limit from 2022–2024 TOI-1518 b transit fits
This earlier SCI study reports shared geometry and duration fits for overlapping TESS observations. It establishes prior scope, not independent confirmation.
- usesSpherical fits of TESS transits with free event times give positive odd flux coefficients for TOI-1518 b in 2022 and late 2024
We use its time coverage rule. We fit an odd flux mode with free event centers. Our code is independent.
- 120 s TESS data show a wider TOI-216 b transit dip in 2025 than in 2023 after local baseline correction
Related SCI work tests transit duration changes with local TESS fits and whole event resampling. This work uses TOI-216 and a direct flux width. No source data or code are reused from the SCI study.
- usesFour tested additive harmonic corrections change TOI-1518 b mean odd transit coefficients by less than 12 ppm
The source study's time-only event rule follows this earlier work. Our result tests brightness changes rather than transit width.