2011AJ....142...49S

We present the proper motion of the sub-parsec-scale jet in a nearby elliptical galaxy 3C 66B. Observations were made at 2.3 GHz and 8.4 GHz at 10 epochs over four years, using the Very Long Baseline Array for all epochs and the Effelsberg 100 m telescope for the last epoch. The 8.4 GHz images showed that the proper motion increases from 0.21 to 0.70 mas/yr, corresponding to an apparent speed of 0.30-0.96c, with a distance from the core on a sub-parsec scale. Our investigation suggests that the apparent increase in the proper motion can be explained by changes in the viewing angle, according to a relativistic beaming model. However, we still cannot eliminate the possibility that acceleration of the jet outflow speed or changes in the emissivity profile in the two-zone jet might be found in 3C 66B.