The gamma-ray spectrometer was a component of starship technology found on the Galaxy-class starships. This component was located near the main navigational deflector in the secondary hull. (Star Trek: The Next Generation)
The name of this component was from the Master Situation Monitor found on Deck 36 of the USS Enterprise-D. It was listed in a grouping of components that included the navigational deflector and the long range sensor array. [[1]]