Closure phases on ALMA-APEX triangles from EHT 2021 April 18 data in band 3. The top panel shows all triangles and the other panels separate out each triangle. Stokes I closure phases are in blue and polarimetric closure phases are in orange. The black line and gray shaded region show the mean and 95% fit region corresponding to Figure 5. The closure phases are offset from zero, consistently with one another, and match the linear fit well. The top ticks convert time to the ALMA-APEX baseline direction measured east of north.