---
aliases:
  - SGTU
---
The **Standard Galactic Time Unit** or **SGTU** is the time unit used for standard communication of time across the many planets and polities of the [[Galactic Cooperation Treaty Organisation]].

It is defined as followed:

SGTU quantities are oft expressed either in binary (for the computers), or hexadecimal (for the normal folks) 1 SGTU is the length $2^{32}$ periods of the wavelength emitted by the [Ly-α](https://en.wikipedia.org/wiki/Lyman-alpha) transition of the Hydrogen atom. This amounts to about 1.74µs

SGTU Timestamps are expressed as a the number of SGTU elapsed since the founding of the GCTO. when written they are typically written in groups of 4 hex digits followed by another delimiter and the number of groups the precision omits, the last group may also contain less than 4 digits in which case the lowest significant digits are assumed to be omitted. e.g. `123F.12/1` is assumed to be equivalent to `123F.12XX.XXXX` (where X is not specified). the start of the timestamp may also be omitted when redundant, in practice it is rare that more than 2 or 3 groups are ever written, unless the activity requires full precision and/or disambiguation.

example:

30 September 2065, 13:12 UTC+2 would be oft rendered as `3D13.65/1` or `18F.3D13.6556.6AD9` for full specificity