XUV stellar spectra. Top panel: panchromatic SED downloaded from the MUSCLES Treasury Survey for GJ1214, GJ832 and HD 97658 and scaled at a distance of 1 AU. The solar spectrum at 1 AU used in the preceding section is shown by the black line. Bottom panel: scaled and binned spectra of our sample of stars. After scaling (see text), the integral over wavelength is the same for all four stars.