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

P. F. L. Maxted , D. Ehrenreich (1) , T. G. Wilson , Y. Alibert (2) , A. Collier Cameron (3) , S. Hoyer (4) , S. G. Sousa (5) , G. Olofsson , A. Bekkelien , A. Deline , L. Delrez , A. Bonfanti , L. Borsato , R. Alonso , G. Anglada Escudé , D. Barrado , S. C. C. Barros , W. Baumjohann , M. Beck , T. Beck , W. Benz , N. Billot , F. Biondi , A. Brandeker , C. Broeg , T. Bárczy , J. Cabrera , S. Charnoz , C. Corral van Damme , Sz. Csizmadia , M. B. Davies , M. Deleuil , O. D. S. Demangeon , B. -O. Demory , A. Erikson , H. G. Florén , A. Fortier , L. Fossati , M. Fridlund , D. Futyan , D. Gandolfi , M. Gillon , M. Guedel , P. Guterman , K. Heng , K. G. Isaak , L. Kiss , J. Laskar (6) , A. Lecavelier Des Etangs , M. Lendl , C. Lovis , D. Magrin , V. Nascimbeni , R. Ottensamer , I. Pagano , E. Pallé , G. Peter , G. Piotto , D. Pollacco , F. J. Pozuelos , D. Queloz , R. Ragazzoni , N. Rando , H. Rauer , C. Reimers , I. Ribas , N. C. Santos , G. Scandariato , A. E. Simon , A. M. S. Smith , M. Steller , M. I. Swayne , Gy. M. Szabó , D. Ségransan , N. Thomas , S. Udry , V. van Grootel , N. A. Walton , a Collier Cameron , G Anglada Escudé , C Corral van Damme , Sz Csizmadia , B-O Demory , a Lecavelier Des Etangs , Gy Szabó , Xavier Bonfils (7)

1 ObsGE - Observatoire Astronomique de l'Université de Genève
2 UTINAM - Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213)
3 University of St Andrews [Scotland]
4 LAM - Laboratoire d'Astrophysique de Marseille
5 Universidade do Porto = University of Porto
6 IMCCE - Institut de Mécanique Céleste et de Calcul des Ephémérides
7 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble

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.

Domains: Astrophysics [astro-ph]

P. F. L. Maxted, D. Ehrenreich, T. G. Wilson, Y. Alibert, A. Collier Cameron, et al.. Analysis of Early Science observations with the CHaracterising ExOPlanets Satellite (CHEOPS) using pycheops. Monthly Notices of the Royal Astronomical Society, 2021, ⟨10.1093/mnras/stab3371⟩. ⟨insu-03458286⟩