Monitoring device

From Memory Alpha, the free Star Trek reference

A monitoring device is a type of scanner/transmitter sometimes employed by the Federation to assist in anthropological observation of a species. The device may be used to expand observation capabilities for a species already under observation through a cultural observation post or in place of such a post.

The USS Enterprise (NCC-1701) placed monitoring devices on Delta Theta III to monitor the aboriginal population there in 2270. (TAS: "Bem")