The general relativistic effects in VLBI observations
 of remote objects and the characteristics of foreground
                       gravitators
 
                       V.I.Zhdanov
       Astronomical Observatory of Kiev University
      Observatorna St., 3;   Kiev 254053   Ukraine
        E-mail: AOKU@GLUK.APC.ORG   (To: V.Zhdanov)
 
     We study the idealised situation when the signals of
a  distant  point  radiation source  pass  by  foreground
gravitators.  The  gravitational  effects  on  observable
characteristics are investigated in order to estimate the
masses,  distances  and transversal  velocities  of   the
gravitators.  This consideration may be  of  interest  in
case  (i) of a radio source with small angular separation
from  a  star  of  our Galaxy or (ii) a  source  observed
through a lensing galaxy. The gravitational contributions
to  the VLBI delay time due to the gravitator motion  are
analysed   and   compared  with  the   information   from
observations  of  the trajectory and  brightness  of  the
source   image.  The  autocorrelation  function  of   the
radiation  from  two coherent images of  the  microlensed
source is estimated. The case of a double star gravitator
system  is  considered;  the  periodic  effects  in   the
observable characteristics of the image are calculated.