We present a sample of SRG/eROSITA X-ray sources located in the eastern
Galactic hemisphere (0<l<180 deg), with significant proper motions according to
GAIA eDR3 measurements and whose extragalactic nature has been confirmed. The
catalog consists of 248 extragalactic sources with spectroscopically measured
redshifts. It includes all objects available in the Simbad database and matched
to the identified optical component within a radius of 0.5 arcsec.
Additionally, the catalog includes 18 sources with the spectral redshift
measurements based on observations at the Russian-Turkish 1.5-m telescope
RTT-150. The sources of the catalog are AGNs of various types (Sy1, Sy2,
LINER), quasars, radio galaxies, and star-forming galaxies. The imitation of
significant proper motions can be explained (previously known in astrometry as
the VIM effect) by the presence of transient events on the line of sight in the
field of view of AGN nuclei and quasars (within the GAIA resolution element).
Such astrophysical phenomena may be the supernovae outbursts, tidal destruction
events in AGNs with double nuclei, variability of large-mass supergiants, the
presence of O-B associations in field of view of variable brightness AGN, etc.
A model of flares with a fast rise and exponential decay profile allows to
describe the variable positional parameters of most similar sources observed in
GAIA. This cross-matching approach of the X-ray source catalogs of the
SRG/eROSITA observatory and the optical catalog of the GAIA observatory can be
used as an independent technique for detecting transient events in the
neighborhood of AGN core (on scales of several hundred parsecs in the picture
plane).Comment: 23 pages, 8 figures, 10 table