A Precessing Disc in OJ287?
  Sillanp\"a\"a, {\it et al.} (1996) have demonstrated that the AGN OJ287 has intensity peaks which recur with a period of about 12 years. I suggest that this is the result of the sweeping of a precessing relativistic beam across our line of sight. In analogy to Her~X-1 and SS433, precession is attributed to the torque exerted by a companion mass on an accretion disc. Secondary maxima observed 1.2 years after two of these peaks may be evidence of nodding motion. 
J. I. Katz