well according to some fomula and -20-5(1-3.14) it'll be magnitude -9.3
..that doesn't seem quite right, should be brighter. i'll look at it again.
Even if it exploded right now, we still wouldn't see it for 4,900 years as that's how far away it is.
@bong: It's 4,900 light years away, so we are safe. We'll still get a spectactular lightshow though I think. Any planets unlucky enough to be too close will have to be shielded though.