Starfire by Charles Sheffield
A halfway decent sci fi book about a supernova in our neighborhood. A shield was built to protect earth from the radiation. Situated far enough away and placed in exactly the right spot it would not have to be extremely large. Not sure how "hard" the science was in the book though. What kind of warning time would we have after we discovered the supernova had occured to the time the radiation hit? I.e., does the radiation travel at light speed or not? And if not how much slower?