Multi-epoch, multi-frequency VLBI study of the parsec-scale jet in the
  blazar 3C 66A
  We present the observational results of the Gamma-ray blazar, 3C 66A, at 2.3,
8.4, and 22 GHz at 4 epochs during 2004-05 with the VLBA. The resulting images
show an overall core-jet structure extending roughly to the south with two
intermediate breaks occurring in the region near the core. By model-fitting to
the visibility data, the northmost component, which is also the brightest, is
identified as the core according to its relatively flat spectrum and its
compactness. As combined with some previous results to investigate the proper
motions of the jet components, it is found the kinematics of 3C 66A is quite
complicated with components of inward and outward, subluminal and superluminal
motions all detected in the radio structure. The superluminal motions indicate
strong Doppler boosting exists in the jet. The apparent inward motions of the
innermost components last for at least 10 years and could not be caused by
new-born components. The possible reason could be non-stationarity of the core
due to opacity change.
