Extended Data Fig. 5: Long-term X-ray light curve.
From: A helium-burning white dwarf binary as a supersoft X-ray source
Compilation of X-ray 2σ upper limits (triangles) and detections (filled circles with 1σ error bars) from previous X-ray missions. The upper limits from Einstein, EXOSAT and the XMM-Newton slews have been computed using http://xmmuls.esac.esa.int/upperlimitserver/ with kT = 60 eV and NH = 1021 cm−2 and then transformed to the best-fit XMM-Newton spectral values using WebPIMMS (https://heasarc.gsfc.nasa.gov/cgi-bin/Tools/w3pimms/w3pimms.pl).
