Colour curves of the three candidate objects, together with the colours of the best fitting alternate transients. The top and bottom panels show g–r and r–i, respectively. The first bin for each object starts at zero days, but the bins can be shifted horizontally in an attempt to better fit the colour curve of the transient compared against (given that this is allowed by the rest of the light curve). Bins whose mean observation dates are closest to each other are used to calculate the colour, provided that these bins overlap in time. If there is a detection in only one band used to calculate the colour while the other is a non-detection, the result is a lower or upper limit.