Science / Research Record
When the clock reads 23:59:60
There is a UTC timestamp with sixty in the seconds field.
Inside this record
The exact positive-leap-second sequence, its timekeeping context, and the boundary between UTC and software clock displays.
- A precise, usable claim
- Concise explanation and context
- Linked supporting sources
- Material caveats and a research note
Source check: 2026-10-07. Source: NIST.
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