Contrast c₀(t) during the PASTIS matrix acquisition. After each pair-wise aberrated DH measurement, we flatten the IrisAO segmented DM to measure the drift in the coronagraph floor over the course of the experiment. We subtract this off our data in order to perform an analysis on the differential contrast, Δc. This open-loop contrast degrades gradually over time (note the linear scale). The measured contrast values range from 2.5 × 10⁻⁸ to 8 × 10⁻⁸ during the course of the experiment, but the difference between adjacent measurements is initially on the order of 2 × 10⁻⁸, rising to 1 × 10⁻⁷ later on, which is sufficient for our proposed calibration method. The total duration of the experiment is 45 min.