Pulsar triangulation

Pulsar triangulation is a manner of navigation whereby pulsar frequencies and their geographic light year measurements are used to identify a specific location in space.

In 2153, Denobulan Dr. Phlox of the starship Enterprise was briefly connected to the Borg collective consciousness. During that time, he was able to detect a specific set of numbers being repeatedly transmitted to the Delta Quadrant. Feeding the numbers into the ship's computer, the numbers were revealed to be the spatial coordinates of Earth, suggesting a future invasion – though not for another two hundred years.