Swift/BAT light curves (in the energy range 15–50 keV) of the three Be/X-ray transients discussed in the paper. The orange squares correspond to 4U 0115+63, the pink circles to V 0332+53, the dark stars to GRO J1750−27 assuming that the source is located at a distance of 22 kpc, and the purple diamonds correspond to GRO J1750−27 for an assumed distance of 12 kpc. The BAT count rates of the three sources have been normalised to a distance of 7 kpc using the best estimates for the true source distances (see Table 1). The start times of the different outbursts are listed in Table 1.