NuSTAR Resolves the First Dual AGN Above 10 keV in SWIFT J2028.5+2543
Michael J. Koss et al 2016 ApJ 824 L4
The superior spatial resolution of NuSTAR above 10 keV allowed for the detection of dual active galactic nuclei (AGN) in the source SWIFT J2028.5+2543. This pair has a projected separation of 25.3 kpc.