Crystal gravfeld trap

A crystal gravfeld trap (CGT) is a rare and expensive sensor that uses a synthetic crystal grid to detect and identify fluctuations in the local gravity field. They can be blocked by the presence of mass, not being able to detect a ship on the far side of a planet due to its mass.

CGTs were the only sensor that could reliably detect a ship with an active cloaking device. When Grand Admiral Thrawn blockaded Coruscant with a number of cloaked asteroids, locating them became a top priority. The New Republic did not possess any CGTs, and so was required to attempt to steal one from Bilbringi.