Units of Time

The Empire uses the following units of time, they are used as a standard across the system, but each planet often maintains their own local calendar.

Year
Years are measured as the time the remnants of Terra take to orbit Sol. The Imperial Year calendar starts at 1 IY, which is the equivalent of 324 ES.

Seconds
The Lunar second is the equivalent of 1.05466 old Terran Seconds or, more precisely, the duration of 9,695,101,022 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.

Lunar Calendar
This duration of second is convenient for dividing a Lunar Day into sub sections. On Lunar day/night cycle completes over a month (rather than a day), there are 4 weeks in a month and 7 days in a week. This keeps each day the correct length for a Human circadian rhythm while matching the moons rotation.

6 days are for working and the 7th is a festival day, where most citizens get a day off.

There are 60 seconds in a minute, 60 minutes in an hour and 24 hours in a day.

There are 13 months in a year, plus a additional days to adjust for calendar drift. These amount to 1 day every 4 years, except every 28 years, unless it's also every 252 years. These extra days are traditionally devoted to work in the name of the Emperor, in thanks for his protection form the Jovians.