Official rule text
77.7 STEP 1—ROLL DICE: Each player may use the “Space Cannon” of a space combat, the players may simultaneously use the ability of each of their units on the invaded planet by rolling “Anti-Fighter Barrage” ability of any of their units in the active a specific number of dice for each of those units; this is called system. a space cannon roll. A hit is produced for each die roll that is equal to or greater than the unit’s “Space Cannon” value. a If one or both players no longer have ships in the active system after resolving this step, the space combat ends a If a unit has a “Space Cannon” ability, it is present on its immediately. faction sheet and technology cards. b Players cannot resolve “Anti-Fighter Barrage” abilities b “Space Cannon” is displayed as “Space Cannon X (xY).” during any rounds of space combat other than the first The X is the minimum value needed for a die to produce round. a hit, and Y is the number of dice rolled. Not all “Space Cannon” abilities are accompanied by a (Y) value; a space c This step still occurs if no fighters are present. cannon roll for such a unit consists of one die.