On a winter night in 1979 the Calder Ridge array recorded a strong, clean event lasting roughly twelve seconds. It was not a burst of noise. It had structure. Then it was gone, and in the forty-odd years since, nothing like it has returned.
A one-time event is the hardest kind to study, because there is nothing to compare it against and no way to make it happen again. The Laboratories keep it, described exactly, in the hope that the record is long enough that it will one day recur, and can then be understood. It has not yet.
What the public record includes
Event recorded
A structured twelve-second event is logged at Calder Ridge and placed under immediate review.
Operator reconciliation
Shift notes, weather notes, and local activity logs are reconciled against the event window.
Non-recurrence review
The event remains single-occurrence after the first long-baseline archival search.
Public centroid
A rounded historical centroid is released for browsing only and excluded from automatic scoring.
Review method
- Single-event envelope normalization.
- Fixed-direction reconstruction with restricted station geometry removed.
- Weather, aircraft, and transmitter exclusion review.
- Multi-decade recurrence search against retained station hours.
Ordinary sources checked
- local burst noise
- aircraft overflight
- known transmitter event
- operator or charting error
- Public centroid is rounded for browsing.
- Raw station timing remains restricted.
- Entry is excluded from automated candidate ranking because it has not repeated.