Alliance are a serie of different mods. On the Star Wars GC, you can play the civil war Empire vs Rebel era + Black Sun and soon the Republic and CIS.
This is the type III from the new Small Golan. It is the station with more weapons and it adds a heavy artillery gun. It can make moderate damage at enemy starships but obviously if they are at movement, perhaps you can not target them with success.
Am I right, that you removed buildable space hypervelocity gun from GC?
No.