Sunrise, sunset, twilight, and moon phase — computed from ephemeris, and independently reproducible by anyone.
Authoritative sources exist and publish continuously. Adapter not built.
Times of upper-limb sunrise and sunset for a position and date.
Begin and end times at 6° solar depression.
Begin and end times at 12° solar depression — the horizon-visibility threshold at sea.
Begin and end times at 18° solar depression.
Phase and illuminated fraction for a date and position.
Deterministically computed from ephemeris. Recompute it yourself and you get the identical answer — this is the one lane where you need not take the source's word for anything.
Measured at a fixed station. The record discloses which one and how far it is from you.
An authoritative body's analytical product. Its uncertainty is the source's own.
The one lane with no uncertainty to carry. Given a position and a time, the answer is deterministic and anyone can recompute it and get the same number — so what the seal proves here is not the value but that we published it before the dispute existed. Note that computed twilight is a geometric fact and not a statement about actual visibility, which weather governs.
Not named here yet. Candidate sources for this lane exist and are identified internally, but they have not been verified against the primary documentation — and an unverified source attribution on a public page is the exact mistake this company exists to avoid. They appear here when they have been checked, not before.
Because this is computed rather than observed, the sealed record's job is timing, not authority. The value was always checkable; what was not checkable is that nobody produced it after the fact to suit an argument.
Whether it was dark enough to see, in a collision or an allision. Nautical twilight is a standing question in maritime matters, and the answer has never needed anyone's word for it.
That framing is our analysis of where disputes arise, not a claim of fact about any matter.
We are not capturing this lane today, so there is nothing here to sell you and we are not going to pretend otherwise. What we do want is to know what you would actually ask it. Requests decide what gets built next — that is not a courtesy, it is how the order is set.