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OJ 287 is a BL Lacertae type quasar in which the active galactic nucleus(AGN) outshines the host galaxy by an order of magnitude. The only exception tothis may be at minimum light when the AGN activity is so low that the hostgalaxy may make quite a considerable contribution to the photometric intensityof the source. Such a dip or a fade in the intensity of OJ 287 occurred inNovember 2017, when its brightness was about 1.75 magnitudes lower than therecent mean level. We compare the observations of this fade with similar fadesin OJ 287 observed earlier in 1989, 1999, and 2010. It appears that there is arelatively strong reddening of the B$-$V colours of OJ 287 when its V-bandbrightness drops below magnitude 17. Similar changes are also seen V$-$R,V$-$I, and R$-$I colours during these deep fades. These data support theconclusion that the total magnitude of the host galaxy is $V=18.0 \pm 0.3$,corresponding to $M_{K}=-26.5 \pm 0.3$ in the K-band. This is in agreement withthe results, obtained using the integrated surface brightness method, fromrecent surface photometry of the host. These results should encourage us to usethe colour separation method also in other host galaxies with strongly variableAGN nuclei. In the case of OJ 287, both the host galaxy and its central blackhole are among the biggest known, and its position in the black holemass-galaxy mass diagram lies close to the mean correlation.

Host galaxy magnitude of OJ 287 from its colours at minimum light