Yepe, you are right, only turrets have 360 arc.
rulebook page 18 wrote:
In addition to being inside the attacker’s firing arc,
the closest point of the target ship’s base must fall
within the weapon range shown on the card (see
“Upgrade Card Anatomy” below). If both of these
conditions are met, then the player rolls the number
of attack dice equal to this card’s attack value
(instead of the ship’s primary weapon value).