Using pulsars to define space-time coordinates

Understand

Fully relativistic coordinates have been proposed for (relativistically) running a "GPS" system.

• These coordinates are the arrival times of the light signals emitted by four "satellites" (clocks).
• Replacing the signals emitted by four controlled clocks by the signals emitted by four pulsars defines a coordinate system with lower accuracy, but valid across the whole Solar System.
• We here precisely define this new coordinate system, by choosing four particular pulsars and a particular event as the origin of the coordinates.