Difference of the χ² between the best fit with a satellite and without a satellite as a function of the satellite size and central time of transit, measured in the light curve of the 2010 transit. The red iso-curves are for negative values of Δχ², where the fit with a satellite is better than the fit without satellite. The vertical lines show the central time (short-dashed) and the time of first and fourth contact (long-dashed lines) for the transit of the planet. The upper x-axis provides the projected distance of the satellite to the planet (elongation) for the corresponding central time of the satellite transit (T_0s).