Result of the model-fit for the cluster “A” (upper panel) and clusters “B” + “C” (lower panel). The colored map shows the distribution of χ² (calculated using Eq. (20)) around the best-fit position, plotting values from the minimum of χ² up to 50% above the minimum. The color-value conversion code is shown by the wedge on the right of the panel. The white cross shows the position of the minimum of χ². The full white contours show levels of 10%, 20%, 30% and 40% above the minimum value of χ².