OJ 287 far-infrared photometry

It is the strongest known candidate to have a binary singularity in its central engine. We aim to better understand the different emission components by searching for correlated variability in the flux over four decades of frequency measurements.

We combined data at frequencies from the millimetric to the visible to characterise the multifrequency light curve in April and May 2010. This includes the only photometric observations of OJ 287 made with the Herschel Space Observatory: five epochs of data obtained over 33 days at 250, 350, and 500um with Herschel-SPIRE. Although we find that the variability at 37GHz on timescales of a few weeks correlates with the visible to near-IR spectral energy distribution (SED), there is a small degree of reddening in the continuum at lower flux levels that is revealed by the decreasing rate of decline in the light curve at lower frequencies.