Automated Siege Cannon

Range: 1100 units
Damage: 165 ( AoE )
AoE Radius: 1100 units
Rate of Fire: 0.25 shots/sec
Build time: 10 seconds
Cost: 15 resources
Health: 2000

From NS community wiki

Automatically acquires the nearest enemy structure (not player) it can "see" and focuses a devastating blast at its location. The siege cannon can fire through walls or obstacles at a range of up to 1100 units, but only if the target is "painted" by a marine spotter (any friendly who can see it) or a commander's scanner sweep (see above). Enemies caught standing next to a blast also take heavy damage.