Sensor pod

A sensor pod was a module that could be connected to the dorsal surface of a starship to extend a starship's sensor capability.

Several Federation starship designs employed this feature, such as the runabout, which was fitted with sensor pods for specific types of missions. 

Other Federation starships with sensor pods of various designs include starships, with two large sensor pods located port and starboard, and  starships, with large sensor pods that resembled large outboard weapons. 

Sensorenmodul