Scatter plot of GOES/XRS low channel peak flux with respect to STIX 4–10 keV count rates scaled to 1 AU for 717 solar flares observed by both GOES and STIX during the cruise phase. The solid line is a linear fit to the log–log graph. The Pearson’s correlation coefficient in the log–log scale is 0.91. From the fit, we get the following GOES flux estimation formula: f = 10^{−7.376 + 0.622log₁₀(X′)} (in units of W m⁻²), where X′ is the STIX peak count rate corrected for the distance variations between the Sun and Solar Orbiter.