Signal-to-noise ratio of OJ 287 detections on April 10, 2017 (top panel), and the corresponding visibility amplitudes of the calibrated data set (bottom panel). Both frequency bands are shown, with scan-long (typically ∼5 min) averaging. Colors follow the convention of Fig. 1. Circle markers denote baselines with ALMA or SMA, while diamonds denote similar baselines to APEX or JCMT.