Is the 25/50 hour timeframe Earth hours, or game hours?

If it's Earth hours, this sounds absolutely terrible to me. That means the Earth day that the event runs would take what, 12 cycles to switch? So what happens to those of us who happen to not be able to log on that particular day? Personally I play on a pretty set schedule so it's entirely possible that will be the case.

Please tell me I'm an idiot and it's Eorzean hours...?