Derivation of suprathermal ion density (n_st) for Solar Orbiter and MMS. (a) Time-varying calibration factor for Solar Orbiter STEP data, derived to correct for dead-time saturation near the shock (red dashed line). (b) Solar Orbiter n_st time series. The density (black) sums the STEP (cyan) and EPT (orange) components. The inset highlights the rapid density increase driven by STEP immediately upstream. (c) MMS n_st time series, combining contributions from FPI (purple, <30 keV) and EIS (green, >30 keV). The vertical red dotted line marks the shock crossing. (d) Combined Solar Orbiter dynamic spectrum (STEP + EPT) used for integration. (e) Combined MMS dynamic spectrum (FPI + EIS). The cyan dashed lines in panels (d) and (e) show the minimum energy used for the suprathermal density integration.