Comparison of ground-based and Gaia photometry of astrometric radio
  sources
  A comparison was made between $Gaia$ magnitudes and magnitudes obtained from
ground-based observations for astrometric radio sources . The comparison showed
that these magnitudes often not agree well. There may be several reasons for
this disagreement. Nevertheless, such an analysis can serve as an additional
filter for verification of the object cross-identification. On the other hand,
it can help to detect possible errors in optical magnitudes of astrometric
radio sources coming from unreliable or inconsistent data sources.
