Earlier quoted context omitted.
Nukes produce lots of gamma and x-rays. On Earth, those are absorbed to produce the fireball. In LEO, some are absorbed by upper atmosphere to make EMP. In space, they are radiation. Except for military satellites like GPS, most satellites aren't hardened to deal with that much radiation. My guess is that the range would be thousands of miles.
I wondered how much energy could pass through some area 1000 miles away from the explosion, so I made some rough calculations. Assumption: all energy of the nuclear explosion is radiation uniform in every direction. The energy E would be spreading in a sphere with area 4*pi*R^2. Area A being a part of that sphere would capture E*A/(4*pi*R^2) of energy. So with: energy E = 209 PJ (Tsar bomba for an extreme example) ar…
I found that satellites get 100-1000 rad per year. Getting that much in a moment would cause problems.