The time of the lowest brightness of OJ 287 since 1995 is within the limits of the prediction of the time of the 1998 (Pietilä 1998). The observations show a sharp peak and subsequent fade at , which is seen on R,V, and I bands. The others lack data from the same time period. Only R and V band data show the deep minimum (with large errorbars), and also the I band minimum is the lowest magnitude since 1995. If the points with large errorbars are removed, the minima, in all the bands B, V, R, and I, still show the lowest brightness of OJ 287 since 1995.
We do not have the exact answer to what caused the 1998 minimum, but the coincidence of the time of the minimum with the prediction of the Lehto & Valtonen (1996) model shows that the suggestion of the binary black hole system is probably relevant, although the details of the various mechanisms remain to be clarified.
© European Southern Observatory (ESO) 1999
Online publication: April 28, 1999