Field referenceGrant fields
first_seen_at
When we first saw this notice, which is not when the source posted it.
first_seen_at is the timestamp of the first crawl in which this notice
appeared to us.
It is deliberately separate from posted_at, which is the source's own posting date. They are different facts and frequently different dates: a notice posted before we connected its feed is seen late, and saying otherwise would misrepresent both our coverage and the programme's timeline.
Shown as: on the newly-added slice, and in freshness reporting. When absent: never.