referenzzeit

Referenzzeit is a German term for a specified moment in time used as a baseline for time measurements, data timestamps, synchronization, and dating across disciplines. It denotes a reference point rather than a fixed standard in itself, enabling consistent comparisons and data integration.

In astronomy, the referenzzeit is often the reference epoch, such as J2000.0, used to express and compare celestial coordinates. In metrology and timekeeping, the reference time is provided by time scales like TAI and UTC; UTC includes leap seconds to stay aligned with Earth's rotation, while TAI runs continuously without leap seconds. In computing and data logging, a common referenzzeit is the Unix epoch, 1970-01-01 00:00:00 UTC, used to stamp timestamps. In navigation and geodesy, GNSS time (for example GPS time) serves as a high-precision reference for time transfer and synchronization between systems.

Choosing and documenting referenzzeit is important for correct interpretation and interoperability; conversions between time scales involve offsets and, in some cases, relativistic corrections. The concept underlines traceability to the SI second and the need to specify the exact scale, epoch, and any adjustments used.

Related concepts include epoch, time stamp, and time scale.