Celestia Forums

I guess taht this is not really a bug, but a simple pitfall.
If you set revese time a go back you'll arrive to year 1 a.C.
and then you'll reach the year 0 , but year zero has never
been counted . And in this way all the date before Christ
are in error of exactly one year .
I think is not a big trouble to subtract one to all years before 1 a.C.

The historical calendar doesn't have a year zero, but the astronomical calendar does. (Some would say there's a bug in the historical calendar ) So the astronomical Year Zero = 1BC, -1 = 2BC, -2 = 3BC, and so on as you say.
The fact that astronomers have used a year zero since the eighteenth century makes the fuss they made about the millennium even more hilarious than it already was. The absence of a year zero meant, they said, we had to wait until the end of 2000 to celebrate the start of a new millennium. But they, of all people, should have been celebrating at the end of 1999!

Grant