TEST OF PERIODICITY IN THE QUASAR OJ-287

OJ 287 displays an apparent periodicity in its violent optical light v ariations. By applying a progressively brighter faint-magnitude cutoff of the data when performing time series analyses of the light curve, the best-fit period is found to increase from 11.7-12.1 yr (depending on the method used) to 12.4 yr (based on an analysis of only the times of light maximum). In comparison, the average time interval between l arge outbursts is 11.7 yr. The derived period exhibits noticeable inst ability, which cannot be caused by the very slow modulation of the lig ht curve or by the double-peak structure of the light maxima. Moreover , the probability of obtaining such a periodicity by chance in the 105 years of past observation is at least 0.02. Nevertheless, arguments b ased on the observed repetition of structure in the light curve, combi ned with a binary black hole model, suggest that a real underlying per iodicity does exist.