Expected performances of the Characterising Exoplanet Satellite (CHEOPS). I. Photometric performances from ground-based calibration

Adrien Deline; Didier Queloz; Bruno Chazelas; Michaël Sordet; François Wildi; Andrea Fortier; Christopher Broeg; David Futyan; Willy Benz

doi:10.1051/0004-6361/201935977

arXiv · 1908.01636

Expected performances of the Characterising Exoplanet Satellite (CHEOPS). I. Photometric performances from ground-based calibration

Adrien Deline·Didier Queloz·Bruno Chazelas·Michaël Sordet·François Wildi·Andrea Fortier·Christopher Broeg·David Futyan·Willy Benz

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Abstract

The Characterising Exoplanet Satellite (CHEOPS) is a space mission designed to perform photometric observations of bright stars to obtain precise radii measurements of transiting planets. The high-precision photometry of CHEOPS relies on careful on-ground calibration of its payload. For that purpose, intensive pre-launch campaigns of measurements were carried out to calibrate the instrument and characterise its photometric performances. We report on main results of these campaigns, provide a complete analysis of data sets and estimate in-flight photometric performance by mean of end-to-end simulation. The on-ground photometric stability of the instrument is found to be of the order of 15 parts per million over 5 hours. Our end-to-end simulation shows that measurements of planet-to-star radii ratio with CHEOPS can be determined with a precision of 2% for a Neptune-size planet transiting a K-dwarf star and 5% for an Earth-size planet orbiting a Sun-like star. It corresponds to signal-to-noise ratios on the transit depths of 25 and 10 respectively, allowing the characterisation and detection of these planets. The pre-launch CHEOPS performances are shown to be compliant with the mission requirements.

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Adrien Deline, Didier Queloz, Bruno Chazelas, Michaël Sordet, François Wildi, Andrea Fortier, Christopher Broeg, David Futyan, Willy Benz. 2019-08-05. Expected performances of the Characterising Exoplanet Satellite (CHEOPS). I. Photometric performances from ground-based calibration. https://doi.org/10.1051/0004-6361/201935977

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