» Thu Jun 21, 2012 12:50 am
http://www.creationkit.com/OnUpdate_(Papyrus) would be the event you'd want for enabling/disabling the parent at certain times.
http://www.creationkit.com/Bethesda_Tutorial_Lights_and_FX#Using_Effects_and_External_Emittance would be if you wanted to do what Alexander described.
To do what you described at the end of your post would basically consist of a mixture of both techniques. Creating three beams, one in the middle and two angled at opposing angles. Set the External Emittance on all of them to that of an FXRegion, then script it so that only the right beam is enabled at sunrise, only the middle at day, only the left at sunrise, and then all three disabled at night.