Structure of OJ 287 from geodetic VLBA data

We have used the Radio Reference Frame Image Database (RRFID) data of the US Naval Observatory (USNO) at 8 GHz to study the structure of OJ 287. The data comprise Very Long Baseline Array (VLBA) observations made during the epochs from 1994 July to 2002 January. The imaging of these data reveals that the position angle of the more collimated unresolved jet rotated clockwise similar to30degrees in 8 yr. The best explanation for this result is given by a ballistic precessing model. The aperture angle of the precessing cone is 3degrees, the axis of the precessing cone forms an angle of 11degrees with the line of sight and has a projected position angle of -107degrees in the plane of sky. The outer structure ( similar to 1.5 mas) of the source is also consistent with a ballistic precessing jet if the velocity of the ballistic component decreases with distance.