OJ 287 is a BL Lac object 4 billion light-years from Earth that has produced quasi-periodic optical outbursts going back approximately 120 years, as first apparent on photographic plates from 1891.

[4] The intrinsic brightness of the flashes corresponds to over a trillion times the Sun's luminosity, greater than the entire Milky Way galaxy's light output.

The optical light curve shows that OJ 287 has a periodic variation of 11–12 years with a narrow double peak at maximum brightness.

An international research group, led by Stefanie Komossa, calculated the mass of the primary black hole.

[10][4] The companion's orbit is decaying via the emission of gravitational radiation and it is expected to merge with the central black hole within approximately 10,000 years.