Variability of the source structure of Sgr A* at 22 (circle), 43 (square), and 86 GHz (diamond) between May 15 and 24, 2007. The source structure is well-fitted by a elliptical Gaussian component. Shown as a function of observing day are: the major axis (top panel), the minor axis (middle panel), and the position angle of the major axis (bottom panel). The corresponding variability indices m are given in boxes on the right side. On May 16 and 19 of May 2007, the data at 86 GHz could only be fitted by a circular Gaussian, therefore no minor axis and position angle are given for these two dates.