Angular distance (see Sect. 5) between the VLBI positions and the respective optical ones determined here as a function of the X-band structure index. Circles: sources where at least one of the offsets, Δα ∗ or Δδ (Table 1, Cols. 11 and 12), were significant (Table 1, Cols. 15 and 16 and Sect. 4). Crosses are given otherwise.
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