Real (black points) and imaginary (red points) parts of the visibilities of project 340.S (previously presented in Qi et al. 2013) in Jy vs deprojected baseline length in kλ. The inset shows the region of 120–420 kλ in greater detail. The dashed black curve shows the recalculated single power-law model of Andrews et al. (2012, their model pC), which fails to reproduce the data on baselines >290 kλ. A much better fit is found for a broken power-law model described in Sect. 3 (solid blue curve). Because both models are symmetric, the imaginary parts of their visibilities are all 0 (not shown).