Magneton
The magneton is a physical constant of magnetic energy. It had several uses in scanning technology, among other things.
While traveling with Dukat in a runabout in 2372, Kira Nerys picked up a faint magneton signature and assumed it could be from a damaged warp nacelle. (DS9: "Indiscretion")
When Miles O'Brien detected high concentrations of tachyons, subspace distortions, and magneton traces later that year, he confirmed that cloaked starships recently passed the area around Deep Space 9. (DS9: "Sons of Mogh")
In 2374, Chakotay used a magneton sweep to detect Reskat for the Ramuran tracer Kellin. (VOY: "Unforgettable")