question about aura abilities

[Madmonkeyman]

So when a unit split fires.  Do all there shots get resolved at the same time.  Ie is a tactical squad fires targeting both dark shroud and a near by scout squad. Normally they would both be -1 to hit due to the dark shrouds aura.  If the dark shroud was killed say by the tac squads las cannon would the marines then be able to fire their bolters at the scouts with out  - 1 to hit.  

 

Just trying to figure out if the aura abilities stay in play till the end of the units shooting attack or do they do away as soon as the unit with the aura is destroyed.

 

As DA with have both azrael and the dark shroud that does this so would be good to know 

[Helycon]

If the DS dies, the other unit no longer benefits from it's aura. The shooting is not simultaneous in that regard. However, if the split fire wasn't enough to kill it, the remaining shots at the scouts will still be at -1.