OGLE photometry. Phases are computed with respect to the photometric circular-orbit T₀ values and periods reported in Table 5. OGLE-III and OGLE-IV magnitudes are shown in grey and black, respectively; the OGLE-III results for VFTS 450 have been offset by (cf. Sect. 2.2). The V- and I_C-band measurements were not quasi-simultaneous, and OGLE-III colours have been computed from phase-binned I_C results, which are ~10× as numerous as the V measurements.