Visibility amplitudes of V1057 Cyg, V2494 Cyg, and V2495 Cyg. In each panel, we plot the azimuthally vector-averaged visibility amplitudes for individual epochs of observations in different colors. Gray symbols and dashed lines show the averaged visibility amplitudes from all available observations. We only present the measured amplitudes which are more than two times higher than the expected amplitude assuming pure noise, to suppress the confusion from some poorly sampled uv distance ranges in our observations. We still cannot fully avoid the issue related to poor uv sampling, which in some cases artificially biases the amplitudes higher at the shortest and/or the longest uv distance.