SKA approach to timestamps in time sensitive data

In ADR-39 it was decided that timestamps for scan data would be harmonised such that they were offsets from a common observatory reference epoch of Midnight on 1 Jan 2000 in TAI (= 1999-12-31T23:59:28Z UTC). This ADR aims to standardise on this approach for other timestamped data, such as delay polynomials and pointing demands.

Why Now: Many ICDs are being finalised and there is an ECP to change timestamps to use TAI https://confluence.skatelescope.org/display/CMI/ECP-230031-+Timestamp+from+UTC+to+TAI

Scope: All software

Quality: Consistency, Interoperability