The bias in closure phase for (solid line), (dashed line), and (dotted line) estimators under a number of measurement conditions. Plots a) and b) show DFT conditions, whilst plots c) and d) show non-DFT conditions (described in the text). Read noise of σ_p = 3e⁻ is present in plots b) and d). The thin and think lines show 120 and 300 photons reaching the detector respectively. The shaded regions in plots c) and d) show the range of possible biases resulting from different possible combinations of phases on the three baselines contributing to the source closure phase.