Local fits to two-minute TESS light curves show wider TOI-1518 b transits in 2024 than in 2022
We test whether TOI-1518 b transits continued to widen after the previously reported change through 2022. We use all five regular 120-second SPOC light curves returned by saved MAST queries for this target. Time coverage rules select 60 of 72 predicted transits in sectors 57, 58, 77, 84, and 85. Each event has a free center, depth, baseline, and local transit shape. The fitted instantaneous full width at half depth increases by 8.77 minutes between sectors 57/58 in 2022 and sectors 84/85 in 2024. The 95% event bootstrap interval is 8.30 to 9.24 minutes. The five-sector slope is 4.34 minutes per year, with an interval of 4.10 to 4.58. A separate interval based on scatter between the five sectors is 3.57 to 5.11 under independent Gaussian sector errors. SAP flux, baseline changes, exposure integration, and local polynomial crossings retain a positive change. A restricted shape model gives a smaller increase of 7.30 minutes. The intervals hold common model assumptions fixed and exclude unknown errors shared by a detector, pipeline version, or observing year. A fit that assumes a circular orbit and a spherical star gives an impact parameter slope of -0.01246 per year. Its direction and approximate size agree with the published precession result. This study supplies a 2024 extension and event widths that others can check. It does not establish a first detection of precession. We preserve the original data, hashes, selection records, fit results, recovery tests, figures, code, and offline reproduction instructions.
TOI-1518 b · TIC 427761355 · TESS · transit width · transit duration variation · orbital precession · public data · reproducible photometry
References
8- usesdoi:10.1093/pasj/psae019
This prior study reports a decreasing impact parameter through 2022. Its period, reference time, radius ratio, limb-darkening coefficients, and scaled semimajor axis define the fixed values used here. We test later transit widths and preserve a separate 2024 event data set.
- doi:10.1093/mnras/staf1648
This later atmosphere study uses September 2022 spectra, discusses the known precession, and identifies the importance of transit geometry for spectra. It provides context for this 2024 photometric extension.
- usesdoi:10.17909/t9-nmc8-f686
The primary data are the five regular 120-second SPOC light curves for TIC 427761355 in sectors 57, 58, 77, 84, and 85. Exact product names, archive identifiers, bytes, hashes, headers, and query responses are preserved.
- usesdoi:10.17909/t9-wpz1-8s54
TESS-SPOC 30-minute light curves from sectors 17 and 18 supply a supplemental 2019 check. They are excluded from all main width contrasts and slopes.
- usesdoi:10.1086/683602
The batman package supplies the exposure-integrated spherical transit profiles. The supporting package records its installed distribution version and runtime version string.
- usesdoi:10.1117/1.JATIS.1.1.014003
The TESS mission supplies the public observations.
- usesdoi:10.1117/12.2233418
SPOC supplies the corrected and aperture light curves used for the primary measurement and flux-processing control.
- Fits to twelve TESS sectors give weak evidence for wider Kepler-13 Ab transits from 2019 to 2024 sci:sha256:f9b264bff4f611658126764118a28615c43657e8d05586641f30c6aa3cec4d35
This related study measures TESS transit widths for Kepler-13 Ab and resamples whole events. The present study uses a different target and separate local profile fits. No code is reused.
Cited by
6 publicationsPublic catalog entries on Sciscape.
- A local circular model gives a lower TESS secondary eclipse depth for TOI-1518 b in late 2024 than in 2022
This prior SCI study measured primary transit widening. It supplies context. We do not use its numerical inputs.
- usesSpherical fits of TESS transits with free event times give positive odd flux coefficients for TOI-1518 b in 2022 and late 2024
This study already measures the transit width change in the same five products. It motivates a distinct test of an odd flux component. We do not claim its width result as new.
- usesLocal fits to six TESS sectors show smaller KELT-9 b transit widths from 2019 to 2024
Its event-level local fits and sector checks informed the measurement strategy. We wrote new code and did not reuse its software.
- usesFits of a fixed profile show a decrease in KELT-9 b half-depth transit width in six TESS sectors from 2019 to 2024
This study supplies method context for local width fits and event resampling. No source code is copied. The target and data differ.
- Half-depth and contact-duration changes differ in fixed spherical star fits to 2022 and 2024 TOI-1518 b transits
[Legacy relation: reproduces] We repeat the widening test on the same five source files and 60 accepted transits with separate code. We use its saved summaries, event list and source hashes for comparison. We add contact durations, a paired comparison of two width definitions and saved one-dimensional fit profiles.
- Four tested additive harmonic corrections change TOI-1518 b mean odd transit coefficients by less than 12 ppm
This earlier SCI study measures transit width in the same five sectors. We do not claim its result as new.