Left:M_G vs. G− J diagram of stars in GCNS that are not found in Gaia DR2. The red dots are new UCD candidates, the blue points are known UCDs (spectral types between M7 and T8), and the grey points are the full GCNS sample. The new candidates are selected following the condition M_G > −3 × (G − J) + 25, after removing stars whose probability of being a WD is higher than 20%. Right: distance distribution of the new candidates in the GCNS (red) and the known UCDs (blue).