Shapes of the six events, determined from the position of the maximum intensity of their average SJ images in the 1400 Å band and plotted in the EW-NS coordinate system. Asterisks refer to event 1, circles to event 2, x’s to event 3, squares to event 4, pluses to event 5 (the main event) and triangles to event 6. Full lines show the penumbra-chromosphere (thin) and the umbra-penumbra (thick) boundaries, measured from the gradient of the continuum images.