ExoClock Project. III. 450 New Exoplanet Ephemerides from Ground and Space Observations

Abstract

The ExoClock project has been created to increase the efficiency of the Ariel mission. It will achieve this by continuously monitoring and updating the ephemerides of Ariel candidates, in order to produce a consistent catalog of reliable and precise ephemerides. This work presents a homogenous catalog of updated ephemerides for 450 planets, generated by the integration of ∼18,000 data points from multiple sources. These sources include observations from ground-based telescopes (the ExoClock network and the Exoplanet Transit Database), midtime values from the literature, and light curves from space telescopes (Kepler, K2, and TESS). With all the above, we manage to collect observations for half of the postdiscovery years (median), with data that have a median uncertainty less than 1 minute. In comparison with the literature, the ephemerides generated by the project are more precise and less biased. More than 40% of the initial literature ephemerides had to be updated to reach the goals of the project, as they were either of low precision or drifting. Moreover, the integrated approach of the project enables both the monitoring of the majority of the Ariel candidates (95%), and also the identification of missing data. These results highlight the need for continuous monitoring to increase the observing coverage of the candidate planets. Finally, the extended observing coverage of planets allows us to detect trends (transit-timing variations) for a sample of 19 planets. All the products, data, and codes used in this work are open and accessible to the wider scientific community.

Characterizing a World Within the Hot-Neptune Desert: Transit Observations of LTT 9779 b with the Hubble Space Telescope/WFC3

“…Data from TESS Sector 2 led to the discovery of LTT 9779 b and it has since reobserved the host star in Sector 29. 32 These TESS data were analyzed by Kokori et al (2023) as part of the ExoClock project (Kokori et al 2021(Kokori et al , 2022, which aims to refine the ephemerides of planets which will be studied by the Ariel mission (Tinetti et al 2018(Tinetti et al , 2021Edwards et al 2019). In our work, we took the TESS midtimes from this previous study and incorporated new unpublished TESS eclipses.…”

“…In our work, we took the TESS midtimes from this previous study and incorporated new unpublished TESS eclipses. As with Kokori et al (2023), we utilize the 2 minute cadence Presearch Data Conditioning (PDC) light curves (Smith et al 2012;Stumpe et al 2012Stumpe et al , 2014. Due to the poor S/Ns of the TESS eclipses, we fit them in groups of four eclipses to achieve eclipse midtime uncertainties that were of a similar precision to the transit measurements.…”

Confirmation and Characterization of the Eccentric, Warm Jupiter TIC 393818343 b with a Network of Citizen Scientists

“…Enlisting such global networks mitigates the limitations faced by professional telescope facilities, such as visibility and weather restrictions of a single location and finite available time. The exoplanet community is already successfully working with these networks through programs such as the Unistellar Network (Peluso et al 2023), Exoplanet Watch (Zellem et al 2020), and ExoClock (Kokori et al 2022(Kokori et al , 2023. Here we add to the quickly growing list of citizen science successes in exoplanet follow-up.…”

Two-dimensional Eclipse Mapping of the Hot-Jupiter WASP-43b with JWST MIRI/LRS

“…We set the orbital period constant at 0.813474 days as it is known with sufficient precision already (Kokori et al 2023). We set the obliquity of the planet to be zero as we assume a tidally locked orbit.…”