The optical jet in 3C 31 on 15 arcsec scales

Evidence has been found for optical emission from the northern radio jet of 3C 31, the radio source associated with NGC 383. The jet emerges from the dust disc and ring of emission at a radius of 5 arcsec, and within 10.4 arcsec is measured to have a B-band flux of 2.1 μJy and an R-band flux of 2.3 μJy. The radio-to-optical spectral index of this region is 0.78. A second connected region, 11.8 arcsec along the jet in position angle 340°, found to have similar optical colours and radio-to-optical spectral index may also be jet emission. We combine our new data with recent radio and X-ray results to conclude that the emission of the jet is synchrotron from the radio to the X-ray.