Identifying Transit Timing Variations in K2 and TESS light curves

Sammanfattning: Aims. The aim of this work is to investigate any presence of transit timing variations (TTVs) in a sample of observed targets that has light curves in both K2 mission data and TESS mission data.  Methods. The original sample utilised here was one from the doctoral thesis of D. Soto (2020) with candidates from K2 data. Cross-referencing for corresponding light curves in TESS was done with a customised Python script created for the purposes of this work, automating the process of obtaining light curves using only one mission ID. A transit search was performed on the light curves of each mission separately with the Python software package OpenTS. The candidates with transits in both light curves were subjected to a TTV search using the Python software package PyTTV. The PyTTV software utilises both mission light curves in creating a joint light curve.  Results. Orbital periods, Porb, and transit center times, t0, for 30 targets were updated using joint light curves from the K2 and TESS missions. Seventeen of these systems are found to have non-linear trends in their transit times. These also have constraints for the periods and amplitudes of the TTVs.  The disposition distribution of the 30 systems is that 19 candidates are unregistered candidates, ten are registered planetary candidates or TOIs and eight are registered known planets.  Conclusions. Out of the reference sample by D. Soto (2020) consisting of 564 targets, 257 targets had a corresponding TESS light curve. Out of the 257 targets, a new sample of 45 targets was contrived through a transit search where they all show distinct transits in both missions light curves. Out of these, fifteen targets were not suitable for a TTV search. A final sample of 30 targets are presented, with seventeen targets showing signs of TTVs and thirteen targets showing a linear trend. The parameters of orbital period and transit centre times are updated for all 30 final candidates. Seventeen candidates are shown to have variations in the transit times and are presented with diagnostics. The candidates with transit timing variations should be further investigated for potential validation or follow-up observations. The unregistered candidates as well as the planetary candidates and TOIs should be considered for follow-up observations or similar validation, to confirm or discard a planetary status.