Plots of closure amplitudes at the X band for source 0454−810 as a function of GMST for two quadrangles, (a) HART15M–HOBART12–KATH12M–YARRA12M and (b) HART15M–KATH12M–YARRA12M–HOBART12. Closure amplitude uncertainties are shown as black bars. The color coding indicates the observing date of the closure measurement, and the corresponding legend is shown on the bottom-right corner of each plot. The station names in the sequence of forming the quadrangle are shown in the first row at the top. Several statistics for the closure amplitudes of that triangle are shown in the second row: the starting date and the ending date of observations in the format of year and month, the CARMS value using uniform weighting, the number of closure amplitudes N_clr, and the number of sessions N_sess. For instance, quadrangle HART15M–HOBART12–KATH12M–YARRA12M has 968 closure amplitudes in 61 sessions with a CARMS value of 0.15 during its entire observing history from 2013-11 to 2017-04. The thin horizontal black lines at 0, −1, and 1 are shown to guide the reading of the variation magnitudes of closure amplitudes. The global CARMS values of 0454−810 are only 0.13, 0.16, and 0.17 based on the three weighting schemes. The small global CARMS values and these two plots suggest that source 0454−810 has minimal structure. The performance of these four southern stations in amplitude observable can also be proven.