Next_new_Moon gives wrong date

[Richard Hollands]

ephem.next_full_moon('2010')
gives:
2010/1/30 06:17:33
but
ephem.next_full_moon('2010-03-21')
gives
2009/9/4 16:02:34

ephem.previous_full_moon('2010')
gives
2009/12/31 19:12:43
but
ephem.previous_full_moon('2010-03-21')
gives
2009/8/6 00:54:50

But set:
d1 = ephem.next_equinox('2010') which makes d1 = 2010/3/20 17:32:09
and
ephem.next_full_moon(d1)
gives
2010/3/20 17:32:09

[Brandon Rhodes (brandon-rhodes)]

That's because the "ephem" library thinks that "2010-03" means the "negative 3" month of 2010 — the third-from-the-last-month of 2009, in other words. You can see this by constructing plain Date objects:

>>> ephem.Date('2010/03')
2010/3/1 00:00:00
>>> ephem.Date('2010-03')
2009/9/1 00:00:00

Are you asking for "-" to become a new date separator character? So far PyEphem has just supported "/", like the astronomy library it is built upon, and so we would have to think through the implications of changing it. I wonder if anybody has ever used the negative-number functionality? I wasn't even sure, until I saw this report, that I myself knew that "2010-03" was even a valid PyEphem date! :-)