The distance two objects pass each other — and the size of the error ellipsoid around each — together define real risk.
The distance two objects pass each other — and the size of the error ellipsoid around each — together define real risk.
Pc is the integral of the combined probability density across the collision cross-section — expressed as a number like 1-in-1,000 or 0.1%.
Most conjunction alerts are driven by poor tracking data, not genuinely close approaches.
Always ask: how old is the tracking data, and how large is the error ellipsoid?