Following in the footsteps of Kepler (Borucki et al. 2010), PLAnetary Transits and Oscillations of stars (PLATO; Rauer et al. 2025) will use high-precision photometry to detect and measure the transits of thousands of exoplanets. A fraction of these planets will exhibit nonlinear ephemerides due to gravitational interactions with other bodies in their systems (Agol et al. 2005; Holman & Murray 2005). These deviations from a linear ephemeris, known as transit timing variations (TTVs), most commonly arise from planet–planet interactions, but can in principle also be induced by additional companions such as exomoons (Kipping 2009). TTVs can therefore be used to detect non-transiting companions and to place dynamical constraints on planetary systems (e.g. Lithwick et al. 2012; Hadden & Lithwick 2017). According to the NASA Exoplanet Archive (Christiansen et al.
The four-year observing baseline of Kepler’s primary mission en-
★E-mail: morgan_mitchell@outlook.com abled the detection of TTVs on a range of timescales for hundreds of planets.

In contrast, the Transiting Exoplanet Survey Satellite (TESS; Ricker et al. 2015), with its 27-day observing sectors, has had more limited success with this method.

Only 60 planets discovered by TESS have been identified as showing TTVs as of February 2026, according to the NASA Exoplanet Archive.

The precision with which transit timings can be measured depends on both the photometric transit signal-to-noise ratio (SNR) and the observing cadence.

Price & Rogers (2014) showed that the uncertainty in mid-transit times is several times larger for light curves with 30-minute integrations compared to those with instantaneous sampling, and that this uncertainty scales approximately inversely with total transit signal-to-noise ratio (SNR).

The possibility of detecting TTVs with PLATO is motivated by its expected multi-year stare durations.

One current proposed observing strategy includes two two-year stares, one in each ecliptic hemisphere, although longer stares remain under consideration (Rauer et al. 2025).

Kane et al. (2019) estimate that around 30 per cent of strong TTV signals from Kepler remain detectable with just one year of data, suggesting that the PLATO baseline will be sufficient to recover TTVs in favourable cases.

PLATO will produce 25-second cadence imagettes for its ∼7,500 bright P1 sample targets in each field (see Rauer et al. 2025 for an overview of the PLATO samples), while most of the fainter P5 sample will be observed at ten-minute cadence.

Previously known exoplanet hosts may also be allocated faster cadence data products.

The effect of cadence on mid-transit timing precision is therefore a relevant consideration.

In addition, PLATO’s photometric precision will vary across its target list with the number of observing cameras and due to factors such as aperture contamination and intrinsic stellar properties.

In this study, we use PlatoSim (Jannsen et al. 2024) to simulate two years of time-series photometry of 152 Kepler host stars containing 361 transiting planets, where at least one planet per system has previously detected TTVs.

In addition to the instrument and detector modelling provided by PlatoSim, the end-to-end simulations incorporate simplified prototype implementations of the onboard and on-ground data processing pipelines.

These prototype pipeline components, developed at LIRA Paris Observatory, approximate the expected photometric extraction and processing steps, although they do not represent the final mission pipelines.

The goal of this work is to assess whether PLATO can recover TTV signals from these systems.

The results identify which Kepler systems are likely to benefit from additional photometric coverage and provide a benchmark for PLATO’s expected performance in this context.

In Section 2, we overview the sample properties and simulation inputs.

In Section 3, we discuss the noise characteristics of the extracted light curves.

In Section 4, we detail the transit fitting process and introduce a timing constraint classification scheme.

In Section 5, we discuss the timing performance across the sample and highlight systems likely to benefit from PLATO follow-up.

Planet Radius (R⊕)
Sample Planets Other Kepler Planets 100 101 102 103 Orbital Period (days) Figure 1.

Period-radius diagram of the 361 sample planets and the remaining 2,331 transiting exoplanets discovered by the Kepler satellite.

The data were taken from the NASA Exoplanet Archive.
the sample to single-star hosts, reducing the number of targets to 165.

Finally, we used the host stars’ temperatures and radii to exclude likely sub-giant hosts, as our stellar variability simulator cannot handle these stars.