We model the binary black hole system OJ287 as a spinning primary and a non-spinning secondary .
It is assumed that the primary has an accretion disk which is impacted by the secondary at specific times .
These times are identified as major outbursts in the light curve of OJ287 .
This identification allows an exact solution of the orbit , with very tight error limits .
Nine outbursts from both the historical photographic records as well as from recent photometric measurements have been used as fixed points of the solution : 1913 , 1947 , 1957 , 1973 , 1983 , 1984 , 1995 , 2005 and 2007 outbursts .
This allows the determination of eight parameters of the orbit .
Most interesting of these are the primary mass of 1.84 \cdot 10 ^ { 10 } M _ { \odot } , the secondary mass 1.46 \cdot 10 ^ { 8 } M _ { \odot } , major axis precession rate 39 ^ { \circ } .1 per period , and the eccentricity of the orbit 0.70 .
The dimensionless spin parameter is 0.28 \ > \pm \ > 0.01 ( 1 sigma ) .
The last parameter will be more tightly constrained in 2015 when the next outburst is due .
The outburst should begin on 15 December 2015 if the spin value is in the middle of this range , on 3 January 2016 if the spin is 0.25 , and on 26 November 2015 if the spin is 0.31 .
We have also tested the possibility that the quadrupole term in the Post Newtonian equations of motion does not exactly follow Einstein ’ s theory : a parameter q is introduced as one of the 8 parameters .
Its value is within 30 % ( 1 sigma ) of the Einstein ’ s value q = 1 .
This supports the no - hair~ { } theorem of black holes within the achievable precision .
We have also measured the loss of orbital energy due to gravitational waves .
The loss rate is found to agree with Einstein ’ s value with the accuracy of 2 % ( 1 sigma ) .
There is a possibility of improving the accuracy of both quantities using the exact timing of the outburst on 21 July 2019 .
Because of closeness of OJ287 to the Sun ( 8 - 12 ^ { \circ } ) , the observations would be best carried out by a telescope in space .