 
  
  
   
Measures change in apparent position resulting from the earths motion
around the sun
 
  requires radio interferometry
   requires radio interferometry
 
  MERLIN or VLBI
   MERLIN or VLBI
 
  B0823+26
   B0823+26   
 
 
  B0950+08
   B0950+08   
 
 
  B1451-68
   B1451-68   
 
 
  B1929+10
   B1929+10   
 
 
  B1929+10 <4
   B1929+10 <4
 
  Geminga optically
   Geminga optically