BL Lacertae Object 3C 66A

Movie (1.0 MB AVI) of the evolution of the parsec-scale jet of the quasar 3C 66A. 1 mas = 5.7 parsecs for a Hubble constant of 65 km/s/Mpc. The red contours show total intensity (starting at 64% of the peak and decreasing by factors of 2), while the colored image corresponds to linearly polarized intensity. The white sticks show the direction of the electric vector; the magnetic field is perpendicular to the electric vector except perhaps in the most compact components, which might be opaque. The lavender vector on the right shows the 230 GHz polarization of the entire object as measured by the James Clerk Maxwell Telescope. The inset shows the brightness (flux density) as measured by the JCMT, with the red arrow showing the current date of the animation and green arrows showing epochs of actual observations. The movie is made by linear interpolation of the data. There is an unresolved stationary feature on the top (northern) end, customarily called the "core." During the movie, the contours change as if an extremely rapid wave of brightening moves down the jet. Further analysis is required to determine whether this is just an illusion of the process used to make the movie. The most interesting feature of 3C 66A is its very high polarization at 230 GHz, as high as 57% in May 1998. The radio polarization is only about 3%. However, the movie shows an apparent polarizing wave (which also might be an artifact of the movie-making process) that causes the polarization of the jet to peak at about the same time as the maximum 230 GHz polarization. This movie was made by Svetlana Jorstad from data analyzed by her and Alan Marscher, in collaboration with T. Cawthorne, A. Stirling, M. Lister, W. Gear, J. Stevens, D. Gabuzda, E.I. Robson, J.R. Forster, and P. Smith.