I'm still missing something
The first time I heard about using a nuke to deflect an asteroid in space I found the idea ridiculous - and I still do.
Nukes on Earth have a devastating effect because of the air - it is the tremendous force of the explosion acting against the atmosphere that creates the shockwave which blows everything away that has not been incinerated by the initial radiation.
But in space, there is no atmosphere. So there can be no shockwave, and that removes 100% of the mechanical effects of a nuke.
The only thing I can imagine that remains is the radiation. Now I understand the concept of solar wind, and I can comprehend that a nuke may shine a boatload of radiation on the side of an asteroid, but frankly I fail to see how that could change the asteroid's course in a meaningful way.
It would more likely take a dozen nukes, at specific points of the orbit, to induce any serious change of orbit. Especially since a nuke explosion goes in all directions, so even in the very best of cases, 50% of the energy still radiates away from the asteroid, and the further away the nuke is, the less energy the asteroid will get.
To me, it feels a bit like trying to move a car by blowing on it. I just can't imagine it'll work.
White paint on one side seems a lot better. Let the Sun do the work whenever that side is showing.