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We present the results from an ultra-high-resolution 7mm Very Long BaselineArray (VLBA) study of the relativistic jet in the BL Lacertae object OJ287 from1995 to 2011 containing 136 total intensity images. Analysis of the imagesequence reveals a sharp jet-position-angle swing by >100 deg. during[2004,2006], as viewed in the plane of the sky, that we interpret as thecrossing of the jet from one side of the line of sight to the other during asofter and longer term swing of the inner jet. Modulating such long term swing,our images also show for the first time a prominent erratic wobbling behaviorof the innermost ~0.4mas of the jet with fluctuations in position angle of upto ~40 deg. over time scales ~2yr. This is accompanied by highly superluminalmotions along non-radial trajectories, which reflect the remarkablenon-ballistic nature of the jet plasma on these scales. The erratic nature andshort time scales of the observed behavior rules out scenarios such as binaryblack hole systems, accretion disk precession, and interaction with the ambientmedium as possible origins of the phenomenon on the scales probed by ourobservations, although such processes may cause longer-term modulation of thejet direction. We propose that variable asymmetric injection of the jet flow;perhaps related to turbulence in the accretion disk; coupled with hydrodynamicinstabilities, leads to the non-ballistic dynamics that cause the observednon-periodic changes in the direction of the inner jet.

Erratic Jet Wobbling in the BL Lacertae Object OJ287 Revealed by Sixteen Years of 7mm VLBA Observations