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

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.

arXiv comment12 pages, 14 figures, accepted for publication in A&A

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• The atmosphere and architecture of WASP-189 b probed by its CHEOPS phase curve
• CHEOPS Precision Phase Curve of the Super-Earth 55 Cnc e
• TOI-5678 b: A 48-day transiting Neptune-mass planet characterized with CHEOPS and HARPS
• Expected performances of the Characterising Exoplanet Satellite (CHEOPS) II. The CHEOPS simulator
• A CHEOPS White Dwarf Transit Search
• A stellar occultation by the transneptunian object (50000) Quaoar observed by CHEOPS
• A Geologically Robust Procedure For Observing Rocky Exoplanets to Ensure that Detection of Atmospheric Oxygen is an Earth-Like Biosignature
• Dark skies of the slightly eccentric WASP-18 b from its optical-to-infrared dayside emission
• Glancing through the debris disk: Photometric analysis of DE Boo with CHEOPS
• Searching for technosignatures in exoplanetary systems with current and future missions