Two-dimensional histogram (δm–δt) of the Bsg 2dFS1053 from the OGLE II data, where the colour gradient marks the density of the points (see the colourbar). The dashed line marks the 10σ level of the random photometric uncertainty, while the solid line differentiates variations above the 0.1^m level. The δm–δt two-dimensional histograms of the remaining Bsgs are included in Fig. C.1.