CHEOPS throughput. Left: normalised CHEOPS throughput as a function of wavelength. For comparison, normalised Gaia, Kepler, TESS, and PLATO throughput are also plotted. Note the similarity between CHEOPS and Gaίa throughput. Right: CHEOPS integrated throughput as a function of the star’s spectral type using PHOENIX model for the SED (Hauschildt et al. 1999a,b). This represents the fraction of all incident photons in the 330 nm to 1100 nm wavelength range converted into photoelectrons.