# Transit analysis of the CoRoT-5, CoRoT-8, CoRoT-12, CoRoT-18, CoRoT-20, and CoRoT-27 systems with combined ground- and space-based photometry

## TL;DR

This study combined ground- and space-based photometry over several years to refine the orbital parameters of six CoRoT-discovered transiting exoplanets, improving ephemeris accuracy and searching for additional bodies.

## Contribution

It provides updated orbital and physical parameters for six CoRoT exoplanets using extensive follow-up observations, with improved ephemeris precision and constraints on system dynamics.

## Key findings

- Refined orbital periods with uncertainties reduced by up to 33 times.
- Detected transit timing deviations up to ~115 minutes in five systems.
- Failed to detect transit for CoRoT-27b in the predicted window.

## Abstract

We have initiated a dedicated project to follow-up with ground-based photometry the transiting planets discovered by CoRoT in order to refine the orbital elements, constrain their physical parameters and search for additional bodies in the system. From 2012 September to 2016 December we carried out 16 transit observations of six CoRoT planets (CoRoT-5b, CoRoT-8b, CoRoT-12b, CoRoT-18b, CoRoT-20b, and CoRoT-27b) at three observatories located in Germany and Spain. These observations took place between 5 and 9 yr after the planet's discovery, which has allowed us to place stringent constraints on the planetary ephemeris. In five cases we obtained light curves with a deviation of the mid-transit time of up to ~115min from the predictions. We refined the ephemeris in all these cases and reduced the uncertainties of the orbital periods by factors between 1.2 and 33. In most cases our determined physical properties for individual systems are in agreement with values reported in previous studies. In one case, CoRoT-27b, we could not detect any transit event in the predicted transit window.