pub fn observed_arrival_nanos(
event_nanos: i64,
distance: &Quantity,
) -> Option<i64>Expand description
The instant (nanoseconds since the epoch) at which an event happening at event_nanos is
observed by someone a distance away — event + distance/c. The relativistic light-delay the
space-travel time model is built on. None if distance is not a length or the result overflows.