New Stardate was a type of timekeeping system in use by the Federation after all the space-faring races of the Milky-Way galaxy united under its banner some time in the far distant future.
Dates in this system were expressed as γ nnnn.nn.n.
The Enterprise encountered the Preserver inter-dimensional gateway in inter-galactic space on New Stardate γ 2143.21.3. (ST novel: Federation)