1.3 mm amplitude (open blue circles, left axes) and S/N (filled red squares, right axes) vs. the duration of coherently integrated segments, which are incoherently averaged. Each subplot shows a different polarization on the baseline between ALMA and IRAM30m for a single scan on BL Lac on October 19, 01:13 UTC. Other BL Lac detections listed in Table 2 have a similar dependence on segment duration. The noise-debiased amplitude and coherence time were derived using HOPS and are indicated by the horizontal blue dashed line and the vertical solid black line, respectively. These data were calibrated in the same manner as the 870 μm detections.