Estimates of the closure phase of Vega (blue squares) and Deneb (red triangles) with rescaled error bars, corresponding to the contributions of four sub-pupils numbered 1, 2, 6 and 13: a) 1-2-6; b) 1-2-13; c) 1-6-13; d) 2-6-13. Each estimate corresponds to 10 s of observation (average of 50 images of 200 ms integrations). The error bars represent the standard deviation of the mean over the 50 frames (i.e. the frame-to-frame standard deviation weighted by the modulus of the bispectrum divided by ). The gray rectangles represent the periods when no data were taken.