OJ 287 and the predicted fade of 1998

There were predictions that blazar <ASTROBJ>OJ 287</ASTROBJ> should have faded in late 1997 or early 1998. The observational background for these predictions is the sudden fade of <ASTROBJ>OJ 287</ASTROBJ> in 1989. Back then, the radio flux decreased steadily for 4-5 months and then the brightness dropped also in the optical region suddenly for 2-3 weeks to all time low values, e.g. V=17.4 mag. The predictions are based on a binary black hole model, where the companion black hole and its accretion disk eclipse the emission areas of the primary black hole. We have made observations of <ASTROBJ>OJ 287</ASTROBJ> during the time of the predicted fade. The results show that, in the optical, <ASTROBJ>OJ 287</ASTROBJ> starts to fade almost linearly in December 1997 until mid-February 1998, when it suddenly shows a sharp rise and sharp fade, and starts to get brighter again. The radio observations show no signs of variability, but the radio flux has been very low since the 1995 outburst. We also have earlier observations since Fall 1993 to Spring 1998, which show that the local minimum reached in February 1998 was the lowest since 1995. We have made observations with several telescopes in the optical (UBVRI) and radio (22 and 37 GHz) bands. We discuss the various events in the light curves and their implications on the proposed models, especially the binary black hole model by Lehto & Valtonen (\cite{lv96}), which was used to make the prediction of the time of the fade. Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, observations at the Perugia Observatory, Perugia, Italy, observations at the Observatorio Astronómico Nacional, San Pedro Mártir, Baja California, México, observations at the Torino Observatory, Torino, Italy, observations at the Tuorla Observatory, Piikkiö, Finland, and observations at the Metsähovi Radio Research Station, Metsähovi, Finland.