Five TESS sectors give no clear linear increase in KELT-21 b transit width from 2021 to 2024
We test whether later TESS data show a continued increase in the transit width of KELT-21 b after an uncertain change reported in 2022. Coverage rules select 29 complete transits in five public two-minute SPOC light curves from 2021 to 2024. We fit a common spherical transit profile with a free width, center, depth, and local baseline for each event. The measured width is the intrinsic full width at half depth. It is not a physical contact duration. An equal-weight linear fit to five sector means gives +0.140 minutes per year. A residual Student t interval with three degrees of freedom spans -1.738 to +2.017 minutes per year. The later four sectors exceed the first by 2.040 minutes, with a conditional whole-event interval from 0.775 to 3.229 minutes. This positive contrast does not establish a linear increase. Aperture flux, local baseline, template shape, and separate sector spline controls all give trend intervals that include zero. Residual-shift trials recover input slopes of zero and +2 minutes per year under the tested noise model. Detector and time effects remain partly mixed. These data permit a slow width increase but do not resolve a steady increase under the sector error model. They do not measure a physical precession rate. We preserve the five source FITS files, exact provenance, event decisions, result tables, figures, source code, and instructions for a new run.
KELT-21 b · TESS · transit width · transit duration variation · orbital precession · public photometry · reproducible astronomy
References
7- usesdoi:10.1093/mnras/stac1095
The uncertain duration increase motivates this later TESS test. Table 10 supplies the approximate ephemeris. Earlier shape values define a nominal profile; every event has a free center and width. We measure a different width from physical contact duration.
- doi:10.3847/1538-3881/aaa5af
The discovery paper identifies KELT-21 b and the star's rapid rotation.
- usesdoi:10.17909/t9-nmc8-f686
TESS two-minute SPOC light curves for TIC 203189770 in sectors 41, 55, 75, 81, and 82 supply the measurements. The package records exact product names, URLs, retrieval times, sizes, and hashes.
- usesdoi:10.1086/683602
The batman package, version 2.5.2, supplies the nominal spherical transit profile. We normalize and scale that profile to measure width, without a physical precession inference.
- usesdoi:10.1117/1.JATIS.1.1.014003
The TESS mission supplies the public photometry used in this test.
- usesdoi:10.1117/12.2233418
The SPOC pipeline supplies the aperture and corrected light curves used in this test.
- usesFits to twelve TESS sectors give weak evidence for wider Kepler-13 Ab transits from 2019 to 2024 sci:sha256:f9b264bff4f611658126764118a28615c43657e8d05586641f30c6aa3cec4d35
Its empirical width workflow and error controls helped define this test. We use new code and separate source data.
Cited by
4 publicationsPublic catalog entries on Sciscape.
- usesLocal fits to nine TESS sectors show no clear linear change in TOI-1431 b transit width from 2019 to 2024
This related transit width study supplies method ideas for sector trend intervals and conditional recovery from shifted residuals. No source code was copied.
- Local fits to five TESS sectors show wider KELT-17 b transits in 2023 than in 2021
This KELT-21 width study gives workflow context and explains the distinction between event scatter and sector errors. No code or source data were copied.
- usesThree TESS visits show no clear width trend for HAT-P-69 b in 2021–2025 under an independent visit error model
The study informed the width measure and visit error controls. We wrote new code and used different target data.
- usesFour TESS sectors do not resolve a linear HAT-P-49 b transit width change from 2021 to 2024 under a sector error model
This study informed the empirical width, sector error, and residual recovery workflow. We wrote new code and used different data.