Notes. Best-fit results of the astrometry and relative photometry of WW Cha with 1σ errors. For three PIONIER epochs (runs A, B, and E), multiple minima are found (cf. Sect. 3.2). For the three GRAVITY points, the systematic astrometric errors are estimated for α to be 0.02, 0.01, and 0.01 mas, and for β to be 0.02, 0.05, and 0.01 mas, respectively (see text). For the two GRAVITY epochs with independent image reconstruction (runs G and I), the relative positions and flux ratios resulting from the Gaussian fits (cf. Sect. 3.3) are shown as well. The is the reduced χ²-value of the best fit, taking the degrees of freedom ν into account. The last two columns indicate the H and K band apparent magnitudes for the primary and secondary, assuming the unchanged 2 MASS total magnitudes of m_H = 7.21 ± 0.08 and m_K = 6.08 ± 0.05. In most cases, the relative magnitudes are limited by the 2 MASS uncertainty. The technical details concerning the runs are given in the appendix.