Top panel: HE 1104−1805 R-band light curve obtained by joining three datasets: SMARTS (yellow and blue squares), ECAM (purple and green circles), and WFI (brown and pink triangles). For clarity, the light curve of B was shifted by –1.05 mag. The inset zooms on the WFI dataset span, showcasing its superior sampling to the ECAM dataset. Bottom panel: Example of a simultaneous fit of an intrinsic light curve with η = 45 days and n_ml = 15. The time shift obtained by this fit gives a point estimate of the system’s time delay. By repeating such measurements with randomised starting points 800 times, we obtained the time-delay measurement of this (η, n_ml) configuration.