Analysis of Early Science observations with the CHaracterising ExOPlanets Satellite (CHEOPS) using pycheops

TL;DR

This paper demonstrates the effective analysis of CHEOPS early science data for four exoplanets using the pycheops software, achieving precision comparable to larger space telescopes and providing new insights into their internal structures.

Contribution

The paper introduces pycheops, an open-source tool for analyzing CHEOPS light curves, and validates its effectiveness with real data from four exoplanets.

Findings

CHEOPS achieves transit parameter precision comparable to Kepler and Spitzer.

Updated exoplanet parameters lead to new internal structure constraints.

pycheops simplifies and standardizes CHEOPS data analysis.

Abstract

CHEOPS(CHaracterising ExOPlanet Satellite) is an ESA S-class mission that observes bright stars at high cadence from low-Earth orbit. The main aim of the mission is to characterize exoplanets that transit nearby stars using ultrahigh precision photometry. Here we report the analysis of transits observed by CHEOPS during its Early Science observing programme for four well-known exoplanets: GJ436b, HD106315b, HD97658b and GJ1132b. The analysis is done using pycheops, an open-source software package we have developed to easily and efficiently analyse CHEOPS light curve data using state-of-the-art techniques that are fully described herein. We show that the precision of the transit parameters measured using CHEOPS is comparable to that from larger space telescopes such as Spitzer Space Telescope and Kepler. We use the updated planet parameters from our analysis to derive new constraints on the internal structure of these four exoplanets.