All turret weapons in EVE have a tracking attribute which specifies how fast a turret can turn to track a target. It uses radians per second as unit which comes in very handy for calculations.
This is the formula:<cite_reference_link>
In case it isn't obvious, that's 1/2 to the power of [big blob] or 2 to the power of -[big blob]. As one would expect for a probability, the formula is dimensionless.