Here's the 2011 announcement "Nearby galaxy boasts two monster black holes".

and journal paper "Chandra Discovery of a Binary Active Galactic Nucleus in Mrk 739"

I also observed this galaxy a year ago through Jimi's scope. It's located only ½° southwest of Copeland's Septet (HCG 57)!

At 697x; moderately bright, round, 30" diameter. The two stellar nuclei were cleanly resolved, separated by only 6" E-W. The eastern nucleus seemed slighter brighter or more stellar-like. The western nucleus was quasi-stellar (perhaps a few arseconds diameter).