Which method includes tracking where an outside source produces tracking energy?

The method that includes tracking where an outside source produces tracking energy is semi-active tracking. In this approach, a target is illuminated by a source of energy that is not part of the tracking system itself, such as a radar or laser from an external system. The tracking system then detects the energy that reflects off the target to gauge its position and movement.

This technique contrasts with active tracking, where the system emits its own energy source to track the target, making semi-active tracking particularly useful when it benefits from an external illuminator, often enhancing the accuracy and reducing the power requirements of the tracking system.

In passive tracking, the system relies solely on the emissions or reflective characteristics of the target itself, without any assistance from an external source of tracking energy. Indirect tracking does not fit the context of specifically tracking energy produced by an outside source, as it generally refers to methods that infer position through other means rather than direct energy tracking.