Finding an avatar.

Im trying to make a new weapon system, and I'm trying to figure out how to locate a hostile avatar (defined by a seperate notecard) and shoot him with my missile. I've already figured out most of it, but i still cant find a way to get the avatars position and get the missile to go there.
Can anyone help?

Sensor maybe?

As Winter stated a sensor, but that is limited to 96m.

I also query why you would use a notecard to define your target, seems rather longwinded to me.

I'm using a notecard so as to allow others to add people to the list when they buy it.
This is to ensure that they can defend against those that they want to, and not their freinds.

Ah more of a fixed emplacement /auto weapon rather than a hands on type thing?

RIGHT! Its more of a home defense type of thing, and im making anti-physics rounds for it.
So itll generally be an all around defense weapon.

Any other ideas? If not, could you explain how to use the sensor?
Im not new at scripting, but not so great at it either =)

Here is a link to the ExampleProximityDoor script...

http://www.lslwiki.com/lslwiki/wakka.php?wakka=ExampleProximityDoor

The script is a good example of starting and stopping a sensor and using the llDetected* functions (llDetectedName in this case) to determine what was found.

-2fast