What brevity term acknowledges sighting a specified reference point (either visually or via sensor)?

The correct answer, "Contact," is used in military communication to indicate that a unit has observed a specified reference point, whether through direct viewing or by using a sensor. This term is essential for effective coordination and situational awareness among units, as it confirms that the reference point is acknowledged and pertains to the ongoing operation.

In contrast, "Visual" typically refers to seeing an object or position clearly, but it does not specifically denote that there is a confirmed acknowledgment of a reference point. "Spot" also indicates the location of something but does not necessarily convey the same level of confirmation as "Contact." "Joy" is often used to express a high level of excitement or satisfaction, but it lacks the operational clarity required when referencing the identification of a target or reference point. Therefore, "Contact" is the most appropriate term in this context for confirming sighting the specified reference point.