At 00:00:00 hours January 1, 2323, a new Stardate system came into use. Under this new system, 1000 Stardates equals one Earth year, or 365.2425 days (8765.82 hours). One SD equals 8 hours 45.95 minutes. This standard now defines the length of a ship's crew shift, with a standard ship's day being 3 Stardates, or 26 hours 17.85 minutes. This time period happens to be closer to the Human Circadian rhythm than Earth's actual 24 hour day.
Stardate 00000.000 was 00:00:00 UCT 01/01/2323. Taking the year 2376, a leap year, as an example, SD 53000.000, the ship's official New Year, is actually 17:27:36 Universal Coordinated Time, 01/01/2376. Holidays are celebrated on board ship beginning at the start of the shift closest to midnight UCT of that day, with the exception of the New Year which is fixed to the XX000.00 mark; and certain religious holidays, the observance of which is tied to the time at a particular geographical location.
Stardate Conversions for the Year 2376