The accelerator cannon was a type of ship-mounted weapon system used by the Federation Starfleet, on starships that were in use around the turn of the 23rd century. The weapons would work by running a nuclear warhead through a special charger, enhancing the missile's damage and accuracy. The missile would then be fired, at either warp or sublight speeds, a noticeable improvement over the old nuclear launch racks of the 22nd century, which were confined to sublight. (RPG reference book: Starship Construction Manual, 2nd Edition)