Stiletto said:
Pretty sure the max is 4800 per 12 hours
That's 400/h, like redbeard said. :-) Yes, that's the max for an active heaven (redbeard's formula is correct too).
For those who haven't logged in for 3-4 days, you multiply with 3/4, for those who haven't logged in 5-6 days you multiply by 1/2, and for those who have been away for a week or longer, the multiplier is 1/4.