This is the map of the Heaven's Gate.
The blue circle is 1500 km (according to their scale bar) so disregard the red ones. The guys from DTB wiki put that there out of scale with their scale bar at the bottom of the
image.

Also, note that according to Dr. Robert Schroeder, the Heaven's Gate area produces synchrotron radiation (it's a real thing) which is the same radiation that makes a contractor glow blue when using their powers.
It's not something that normally comes out of a nuke. Rather, the remnants of the gate should appear as glowing soil, and what not, as is of a typical nuclear fallout coating what remains of it with radiation.
Oh, and Schroeder also says that the gate should still be there, albeit, intangible and invisible.