Comparison of the integrated (200–2400 nm) SIM SSI (iSSI: red) to the TSIS-1 TIM measured TSI (blue). A constant offset of 52.13 Wm⁻² has been added to the integrated SIM to account for the irradiance outside of the SIM measurement range (mostly >2400 nm) to put it on the TIM TSI scale. The agreement with the TSI short-term variability and the long-term trending over the full mission is excellent with an overall difference from the TIM TSI of 0.068 W/m² (<50 ppm, 1σ) over the first five years of continuous observations. The SIM Channel A, B, & C calibration dates noted are the 6-month cadence calibrations to constrain the spectral degradation functions to the SIM channel C observations (see Appendix A for details). New version releases occur after each of these calibrations to provide updates on the stability correction uncertainties by further refinements in the measured spectral degradation functions.