Panel a: TSI reconstruction with the SATIRE-S model using Mt Wilson magnetograms (black circles for daily and ciel line for 180-day running means) along with the Nimbus-7/ERB direct TSI measurements (red triangles for daily and yellow line for 180-day running means). Panels b–c: Comparison between TSI reconstruction with the SATIRE-S model using Mt Wilson magnetograms and direct TSI measurements over the ACRIM-gap (see legends in each panel). Shown are residuals (SATIRE-S with Mt Wilson minus the respective series in each panel) in daily values (black circles) and 180-day running means (yellow lines). The horizontal dashed ciel line marks residuals of 0 Wm⁻². The vertical dashed red line marks the change in Mt Wilson instrumentation over August 1988. The grey shaded surface marks the ACRIM-gap period between July 1989 and October 1991. The right panels show the histogram of the residuals in bins of 0.02 Wm⁻².