χ² map for the binary model fitting of WW Cha for the observations of February 2011 (blue), March 2012 (red), and July 2012 (green) (for each colour, darker tones mean better χ²). The primary is represented by the central black star, while the best fit position of WW Cha companion (i.e., the minimum χ²) is denoted by a cross. Observations of March 2012 produced data of lower quality, leading to numerous local minima in this map.