NGC 6251, a very large radio galaxy with an exceptional jet

Abstract

A newly discovered radio galaxy, NGC 6251, has an angular size of 1○.2, the largest of any in the northern sky. It has a projected physical size of 3.0 Mpc and a remarkable jet which is straight for nearly all of its 200-kpc length. The radio spectral index of the jet is 0.54 and the nucleus has a flat spectrum with a cut-off at low frequencies. Although the radio luminosity of the source is low, the total stored energy is comparable with the highest values known.