Microts: Ah, the wonders of time measurement.
The Eldrae have a number of time measurement systems (well, when you’re an interstellar polity, you more or less have to, since local days and years vary all over the place and it’s handy if your time units bear some resemblance to what nature is doing). But there are two systems that are used more or less everywhere, so I’ll talk about those a little.
The first, “weavetime”, is the one that technical systems use internally, and as the basis for all the other systems, because it defines the base unit, the “pulse”. (It’s not actually the fundamental unit, I suppose, because it’s not the Planck time, nor is it a nice clean number in terms of things atomic clocks, etc., actually measure, but it’s the traditional “second”, if you will. It’s actually based on the length of a nominal resting heartbeat as a multiple of the Planck time – roughly 3/4 of an Earth second, in their terms.) And for scientific and technical purposes, weavetime just agglomerates pulses together, producing kilopulses (about a third of a local hour; 21.6 minutes), megapulses (24 local days; 26 of ours), gigapulses (124 of their years, 122.5 of ours), etc.
Weavetime is defined by consensus agreement of baseline clocks located aboard each and every stargate in the plexus, which together produces the “empire time reference frame”, a nice preferred standard by which everyone can agree what the time is despite all the wormhole FTLing. It also includes the standards for the frame-correction algorithms used to synchronize lighthugger starships and other objects moving at inconveniently relativity-invoking speeds up by defining the difference between the absolute pulse (“empire time”) and the local pulse (“wall-clock time”).
Said lighthugger starships, incidentally, generally make their own lives simpler by using “mission elapsed time” internally, thus avoiding having to use a pulse too different in length from everyone else’s, and go back on the local timebase when they arrive.
But weavetime is kind of inconvenient for day to day use – the nearest “day-length” unit, quite apart from not matching any planet anywhere, is the 144-kilopulse unit at 52 Earth hours, which is not that useful.
So for regular living, people use Imperial Standard Time, which in the finest traditions of hegemonists everywhere is essentially the same as planetary time for the eldrae homeworld, only using the precisely calculated weavetime pulse. It’s local time for there, and for everywhere whose day length is too short (e.g., space stations, where the local day can be around an hour), or too long (tide-locked worlds, where the local day can be around a year), or too weird (e.g., moons of gas giants, where argh conventional calendar does not work), to have a practical local calendar; it’s also used universally as the commercial calendar to work out public holidays, the financial year, etc., etc.
IST uses a local day that’s approximately 26 Earth hours long; that time unit is referred to as one “cycle”. It divides it in half precisely into day and night – which works well for their world, which lacks any axial-tilt-equivalent due to not being a conventional planet and so has no day-length variation – and then divides the day into twelve “hours” (~ 65 Earth minutes) and the night into six “watches”; each of these are individually named, although in writing them briefly it’s acceptable to number them instead.
The name actually doesn’t refer to the whole period, but rather to the moment the period centers around, so while an hour is divided into 72 minutes (each ~ 54 seconds), these are counted as 36 “rising” minutes before the named moment, and 36 “falling” minutes after it. Watches are, obviously, divided into 144 minutes, 72 before and 72 afterward. And each minute contains 72 pulses.
The calendar divides the homeworld’s year (333.3 local cycles in length), into 333 cycles with an additional intercalary cycle (“Calibration”) added every third year (and omitted every thirtieth) to fix the lag, in turn divided into 37 weeks of nine cycles each, which pleasingly allows the weeks to fit evenly into the year and make each calendar date the same day of the week. It’s also divided into months (whose length is taken from the period of the more prominent of the planet’s moons, but which no longer follow its phases, since they’re now synchronized with the years) each 27 days long. This, obviously, doesn’t exactly fit into the length of the year, so there are nine intercalary cycles added at various points to make up the slack.